linux-stable.git/kernel, branch v6.2.13 Linux kernel stable tree mm: fix memory leak on mm_init error handling 2023-04-26T12:30:06+00:00 Mathieu Desnoyers mathieu.desnoyers@efficios.com 2023-03-30T13:38:22+00:00 18471cb160b2298908d2d8d99ab8c0b142c752ba commit b20b0368c614c609badfe16fbd113dfb4780acd9 upstream. commit f1a7941243c1 ("mm: convert mm's rss stats into percpu_counter") introduces a memory leak by missing a call to destroy_context() when a percpu_counter fails to allocate. Before introducing the per-cpu counter allocations, init_new_context() was the last call that could fail in mm_init(), and thus there was no need to ever invoke destroy_context() in the error paths. Adding the following percpu counter allocations adds error paths after init_new_context(), which means its associated destroy_context() needs to be called when percpu counters fail to allocate. Link: https://lkml.kernel.org/r/20230330133822.66271-1-mathieu.desnoyers@efficios.com Fixes: f1a7941243c1 ("mm: convert mm's rss stats into percpu_counter") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit b20b0368c614c609badfe16fbd113dfb4780acd9 upstream.

commit f1a7941243c1 ("mm: convert mm's rss stats into percpu_counter")
introduces a memory leak by missing a call to destroy_context() when a
percpu_counter fails to allocate.

Before introducing the per-cpu counter allocations, init_new_context() was
the last call that could fail in mm_init(), and thus there was no need to
ever invoke destroy_context() in the error paths.  Adding the following
percpu counter allocations adds error paths after init_new_context(),
which means its associated destroy_context() needs to be called when
percpu counters fail to allocate.

Link: https://lkml.kernel.org/r/20230330133822.66271-1-mathieu.desnoyers@efficios.com
Fixes: f1a7941243c1 ("mm: convert mm's rss stats into percpu_counter")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/sys.c: fix and improve control flow in __sys_setres[ug]id() 2023-04-26T12:30:04+00:00 Ondrej Mosnacek omosnace@redhat.com 2023-02-17T16:21:54+00:00 b8fa5061d73e201248650281354135ba26ecf9e5 commit 659c0ce1cb9efc7f58d380ca4bb2a51ae9e30553 upstream. Linux Security Modules (LSMs) that implement the "capable" hook will usually emit an access denial message to the audit log whenever they "block" the current task from using the given capability based on their security policy. The occurrence of a denial is used as an indication that the given task has attempted an operation that requires the given access permission, so the callers of functions that perform LSM permission checks must take care to avoid calling them too early (before it is decided if the permission is actually needed to perform the requested operation). The __sys_setres[ug]id() functions violate this convention by first calling ns_capable_setid() and only then checking if the operation requires the capability or not. It means that any caller that has the capability granted by DAC (task's capability set) but not by MAC (LSMs) will generate a "denied" audit record, even if is doing an operation for which the capability is not required. Fix this by reordering the checks such that ns_capable_setid() is checked last and -EPERM is returned immediately if it returns false. While there, also do two small optimizations: * move the capability check before prepare_creds() and * bail out early in case of a no-op. Link: https://lkml.kernel.org/r/20230217162154.837549-1-omosnace@redhat.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 659c0ce1cb9efc7f58d380ca4bb2a51ae9e30553 upstream.

Linux Security Modules (LSMs) that implement the "capable" hook will
usually emit an access denial message to the audit log whenever they
"block" the current task from using the given capability based on their
security policy.

The occurrence of a denial is used as an indication that the given task
has attempted an operation that requires the given access permission, so
the callers of functions that perform LSM permission checks must take care
to avoid calling them too early (before it is decided if the permission is
actually needed to perform the requested operation).

The __sys_setres[ug]id() functions violate this convention by first
calling ns_capable_setid() and only then checking if the operation
requires the capability or not.  It means that any caller that has the
capability granted by DAC (task's capability set) but not by MAC (LSMs)
will generate a "denied" audit record, even if is doing an operation for
which the capability is not required.

Fix this by reordering the checks such that ns_capable_setid() is checked
last and -EPERM is returned immediately if it returns false.

While there, also do two small optimizations:
* move the capability check before prepare_creds() and
* bail out early in case of a no-op.

Link: https://lkml.kernel.org/r/20230217162154.837549-1-omosnace@redhat.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf: Fix incorrect verifier pruning due to missing register precision taints 2023-04-26T12:29:58+00:00 Daniel Borkmann daniel@iogearbox.net 2023-04-11T15:24:13+00:00 71035a0508c04827b91a5bfeb2c9ef374f321e65 [ Upstream commit 71b547f561247897a0a14f3082730156c0533fed ] Juan Jose et al reported an issue found via fuzzing where the verifier's pruning logic prematurely marks a program path as safe. Consider the following program: 0: (b7) r6 = 1024 1: (b7) r7 = 0 2: (b7) r8 = 0 3: (b7) r9 = -2147483648 4: (97) r6 %= 1025 5: (05) goto pc+0 6: (bd) if r6 <= r9 goto pc+2 7: (97) r6 %= 1 8: (b7) r9 = 0 9: (bd) if r6 <= r9 goto pc+1 10: (b7) r6 = 0 11: (b7) r0 = 0 12: (63) *(u32 *)(r10 -4) = r0 13: (18) r4 = 0xffff888103693400 // map_ptr(ks=4,vs=48) 15: (bf) r1 = r4 16: (bf) r2 = r10 17: (07) r2 += -4 18: (85) call bpf_map_lookup_elem#1 19: (55) if r0 != 0x0 goto pc+1 20: (95) exit 21: (77) r6 >>= 10 22: (27) r6 *= 8192 23: (bf) r1 = r0 24: (0f) r0 += r6 25: (79) r3 = *(u64 *)(r0 +0) 26: (7b) *(u64 *)(r1 +0) = r3 27: (95) exit The verifier treats this as safe, leading to oob read/write access due to an incorrect verifier conclusion: func#0 @0 0: R1=ctx(off=0,imm=0) R10=fp0 0: (b7) r6 = 1024 ; R6_w=1024 1: (b7) r7 = 0 ; R7_w=0 2: (b7) r8 = 0 ; R8_w=0 3: (b7) r9 = -2147483648 ; R9_w=-2147483648 4: (97) r6 %= 1025 ; R6_w=scalar() 5: (05) goto pc+0 6: (bd) if r6 <= r9 goto pc+2 ; R6_w=scalar(umin=18446744071562067969,var_off=(0xffffffff00000000; 0xffffffff)) R9_w=-2147483648 7: (97) r6 %= 1 ; R6_w=scalar() 8: (b7) r9 = 0 ; R9=0 9: (bd) if r6 <= r9 goto pc+1 ; R6=scalar(umin=1) R9=0 10: (b7) r6 = 0 ; R6_w=0 11: (b7) r0 = 0 ; R0_w=0 12: (63) *(u32 *)(r10 -4) = r0 last_idx 12 first_idx 9 regs=1 stack=0 before 11: (b7) r0 = 0 13: R0_w=0 R10=fp0 fp-8=0000???? 13: (18) r4 = 0xffff8ad3886c2a00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0 17: (07) r2 += -4 ; R2_w=fp-4 18: (85) call bpf_map_lookup_elem#1 ; R0=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0) 19: (55) if r0 != 0x0 goto pc+1 ; R0=0 20: (95) exit from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm???? 21: (77) r6 >>= 10 ; R6_w=0 22: (27) r6 *= 8192 ; R6_w=0 23: (bf) r1 = r0 ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0) 24: (0f) r0 += r6 last_idx 24 first_idx 19 regs=40 stack=0 before 23: (bf) r1 = r0 regs=40 stack=0 before 22: (27) r6 *= 8192 regs=40 stack=0 before 21: (77) r6 >>= 10 regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1 parent didn't have regs=40 stack=0 marks: R0_rw=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0) R6_rw=P0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm???? last_idx 18 first_idx 9 regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1 regs=40 stack=0 before 17: (07) r2 += -4 regs=40 stack=0 before 16: (bf) r2 = r10 regs=40 stack=0 before 15: (bf) r1 = r4 regs=40 stack=0 before 13: (18) r4 = 0xffff8ad3886c2a00 regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0 regs=40 stack=0 before 11: (b7) r0 = 0 regs=40 stack=0 before 10: (b7) r6 = 0 25: (79) r3 = *(u64 *)(r0 +0) ; R0_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar() 26: (7b) *(u64 *)(r1 +0) = r3 ; R1_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar() 27: (95) exit from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 11: (b7) r0 = 0 ; R0_w=0 12: (63) *(u32 *)(r10 -4) = r0 last_idx 12 first_idx 11 regs=1 stack=0 before 11: (b7) r0 = 0 13: R0_w=0 R10=fp0 fp-8=0000???? 13: (18) r4 = 0xffff8ad3886c2a00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0 17: (07) r2 += -4 ; R2_w=fp-4 18: (85) call bpf_map_lookup_elem#1 frame 0: propagating r6 last_idx 19 first_idx 11 regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1 regs=40 stack=0 before 17: (07) r2 += -4 regs=40 stack=0 before 16: (bf) r2 = r10 regs=40 stack=0 before 15: (bf) r1 = r4 regs=40 stack=0 before 13: (18) r4 = 0xffff8ad3886c2a00 regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0 regs=40 stack=0 before 11: (b7) r0 = 0 parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_r=P0 R7=0 R8=0 R9=0 R10=fp0 last_idx 9 first_idx 9 regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1 parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar() R7_w=0 R8_w=0 R9_rw=0 R10=fp0 last_idx 8 first_idx 0 regs=40 stack=0 before 8: (b7) r9 = 0 regs=40 stack=0 before 7: (97) r6 %= 1 regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2 regs=40 stack=0 before 5: (05) goto pc+0 regs=40 stack=0 before 4: (97) r6 %= 1025 regs=40 stack=0 before 3: (b7) r9 = -2147483648 regs=40 stack=0 before 2: (b7) r8 = 0 regs=40 stack=0 before 1: (b7) r7 = 0 regs=40 stack=0 before 0: (b7) r6 = 1024 19: safe frame 0: propagating r6 last_idx 9 first_idx 0 regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2 regs=40 stack=0 before 5: (05) goto pc+0 regs=40 stack=0 before 4: (97) r6 %= 1025 regs=40 stack=0 before 3: (b7) r9 = -2147483648 regs=40 stack=0 before 2: (b7) r8 = 0 regs=40 stack=0 before 1: (b7) r7 = 0 regs=40 stack=0 before 0: (b7) r6 = 1024 from 6 to 9: safe verification time 110 usec stack depth 4 processed 36 insns (limit 1000000) max_states_per_insn 0 total_states 3 peak_states 3 mark_read 2 The verifier considers this program as safe by mistakenly pruning unsafe code paths. In the above func#0, code lines 0-10 are of interest. In line 0-3 registers r6 to r9 are initialized with known scalar values. In line 4 the register r6 is reset to an unknown scalar given the verifier does not track modulo operations. Due to this, the verifier can also not determine precisely which branches in line 6 and 9 are taken, therefore it needs to explore them both. As can be seen, the verifier starts with exploring the false/fall-through paths first. The 'from 19 to 21' path has both r6=0 and r9=0 and the pointer arithmetic on r0 += r6 is therefore considered safe. Given the arithmetic, r6 is correctly marked for precision tracking where backtracking kicks in where it walks back the current path all the way where r6 was set to 0 in the fall-through branch. Next, the pruning logics pops the path 'from 9 to 11' from the stack. Also here, the state of the registers is the same, that is, r6=0 and r9=0, so that at line 19 the path can be pruned as it is considered safe. It is interesting to note that the conditional in line 9 turned r6 into a more precise state, that is, in the fall-through path at the beginning of line 10, it is R6=scalar(umin=1), and in the branch-taken path (which is analyzed here) at the beginning of line 11, r6 turned into a known const r6=0 as r9=0 prior to that and therefore (unsigned) r6 <= 0 concludes that r6 must be 0 (**): [...] ; R6_w=scalar() 9: (bd) if r6 <= r9 goto pc+1 ; R6=scalar(umin=1) R9=0 [...] from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 [...] The next path is 'from 6 to 9'. The verifier considers the old and current state equivalent, and therefore prunes the search incorrectly. Looking into the two states which are being compared by the pruning logic at line 9, the old state consists of R6_rwD=Pscalar() R9_rwD=0 R10=fp0 and the new state consists of R1=ctx(off=0,imm=0) R6_w=scalar(umax=18446744071562067968) R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0. While r6 had the reg->precise flag correctly set in the old state, r9 did not. Both r6'es are considered as equivalent given the old one is a superset of the current, more precise one, however, r9's actual values (0 vs 0x80000000) mismatch. Given the old r9 did not have reg->precise flag set, the verifier does not consider the register as contributing to the precision state of r6, and therefore it considered both r9 states as equivalent. However, for this specific pruned path (which is also the actual path taken at runtime), register r6 will be 0x400 and r9 0x80000000 when reaching line 21, thus oob-accessing the map. The purpose of precision tracking is to initially mark registers (including spilled ones) as imprecise to help verifier's pruning logic finding equivalent states it can then prune if they don't contribute to the program's safety aspects. For example, if registers are used for pointer arithmetic or to pass constant length to a helper, then the verifier sets reg->precise flag and backtracks the BPF program instruction sequence and chain of verifier states to ensure that the given register or stack slot including their dependencies are marked as precisely tracked scalar. This also includes any other registers and slots that contribute to a tracked state of given registers/stack slot. This backtracking relies on recorded jmp_history and is able to traverse entire chain of parent states. This process ends only when all the necessary registers/slots and their transitive dependencies are marked as precise. The backtrack_insn() is called from the current instruction up to the first instruction, and its purpose is to compute a bitmask of registers and stack slots that need precision tracking in the parent's verifier state. For example, if a current instruction is r6 = r7, then r6 needs precision after this instruction and r7 needs precision before this instruction, that is, in the parent state. Hence for the latter r7 is marked and r6 unmarked. For the class of jmp/jmp32 instructions, backtrack_insn() today only looks at call and exit instructions and for all other conditionals the masks remain as-is. However, in the given situation register r6 has a dependency on r9 (as described above in **), so also that one needs to be marked for precision tracking. In other words, if an imprecise register influences a precise one, then the imprecise register should also be marked precise. Meaning, in the parent state both dest and src register need to be tracked for precision and therefore the marking must be more conservative by setting reg->precise flag for both. The precision propagation needs to cover both for the conditional: if the src reg was marked but not the dst reg and vice versa. After the fix the program is correctly rejected: func#0 @0 0: R1=ctx(off=0,imm=0) R10=fp0 0: (b7) r6 = 1024 ; R6_w=1024 1: (b7) r7 = 0 ; R7_w=0 2: (b7) r8 = 0 ; R8_w=0 3: (b7) r9 = -2147483648 ; R9_w=-2147483648 4: (97) r6 %= 1025 ; R6_w=scalar() 5: (05) goto pc+0 6: (bd) if r6 <= r9 goto pc+2 ; R6_w=scalar(umin=18446744071562067969,var_off=(0xffffffff80000000; 0x7fffffff),u32_min=-2147483648) R9_w=-2147483648 7: (97) r6 %= 1 ; R6_w=scalar() 8: (b7) r9 = 0 ; R9=0 9: (bd) if r6 <= r9 goto pc+1 ; R6=scalar(umin=1) R9=0 10: (b7) r6 = 0 ; R6_w=0 11: (b7) r0 = 0 ; R0_w=0 12: (63) *(u32 *)(r10 -4) = r0 last_idx 12 first_idx 9 regs=1 stack=0 before 11: (b7) r0 = 0 13: R0_w=0 R10=fp0 fp-8=0000???? 13: (18) r4 = 0xffff9290dc5bfe00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0 17: (07) r2 += -4 ; R2_w=fp-4 18: (85) call bpf_map_lookup_elem#1 ; R0=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0) 19: (55) if r0 != 0x0 goto pc+1 ; R0=0 20: (95) exit from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm???? 21: (77) r6 >>= 10 ; R6_w=0 22: (27) r6 *= 8192 ; R6_w=0 23: (bf) r1 = r0 ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0) 24: (0f) r0 += r6 last_idx 24 first_idx 19 regs=40 stack=0 before 23: (bf) r1 = r0 regs=40 stack=0 before 22: (27) r6 *= 8192 regs=40 stack=0 before 21: (77) r6 >>= 10 regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1 parent didn't have regs=40 stack=0 marks: R0_rw=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0) R6_rw=P0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm???? last_idx 18 first_idx 9 regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1 regs=40 stack=0 before 17: (07) r2 += -4 regs=40 stack=0 before 16: (bf) r2 = r10 regs=40 stack=0 before 15: (bf) r1 = r4 regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00 regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0 regs=40 stack=0 before 11: (b7) r0 = 0 regs=40 stack=0 before 10: (b7) r6 = 0 25: (79) r3 = *(u64 *)(r0 +0) ; R0_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar() 26: (7b) *(u64 *)(r1 +0) = r3 ; R1_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar() 27: (95) exit from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 11: (b7) r0 = 0 ; R0_w=0 12: (63) *(u32 *)(r10 -4) = r0 last_idx 12 first_idx 11 regs=1 stack=0 before 11: (b7) r0 = 0 13: R0_w=0 R10=fp0 fp-8=0000???? 13: (18) r4 = 0xffff9290dc5bfe00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0 17: (07) r2 += -4 ; R2_w=fp-4 18: (85) call bpf_map_lookup_elem#1 frame 0: propagating r6 last_idx 19 first_idx 11 regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1 regs=40 stack=0 before 17: (07) r2 += -4 regs=40 stack=0 before 16: (bf) r2 = r10 regs=40 stack=0 before 15: (bf) r1 = r4 regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00 regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0 regs=40 stack=0 before 11: (b7) r0 = 0 parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_r=P0 R7=0 R8=0 R9=0 R10=fp0 last_idx 9 first_idx 9 regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1 parent didn't have regs=240 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar() R7_w=0 R8_w=0 R9_rw=P0 R10=fp0 last_idx 8 first_idx 0 regs=240 stack=0 before 8: (b7) r9 = 0 regs=40 stack=0 before 7: (97) r6 %= 1 regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2 regs=240 stack=0 before 5: (05) goto pc+0 regs=240 stack=0 before 4: (97) r6 %= 1025 regs=240 stack=0 before 3: (b7) r9 = -2147483648 regs=40 stack=0 before 2: (b7) r8 = 0 regs=40 stack=0 before 1: (b7) r7 = 0 regs=40 stack=0 before 0: (b7) r6 = 1024 19: safe from 6 to 9: R1=ctx(off=0,imm=0) R6_w=scalar(umax=18446744071562067968) R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0 9: (bd) if r6 <= r9 goto pc+1 last_idx 9 first_idx 0 regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2 regs=240 stack=0 before 5: (05) goto pc+0 regs=240 stack=0 before 4: (97) r6 %= 1025 regs=240 stack=0 before 3: (b7) r9 = -2147483648 regs=40 stack=0 before 2: (b7) r8 = 0 regs=40 stack=0 before 1: (b7) r7 = 0 regs=40 stack=0 before 0: (b7) r6 = 1024 last_idx 9 first_idx 0 regs=200 stack=0 before 6: (bd) if r6 <= r9 goto pc+2 regs=240 stack=0 before 5: (05) goto pc+0 regs=240 stack=0 before 4: (97) r6 %= 1025 regs=240 stack=0 before 3: (b7) r9 = -2147483648 regs=40 stack=0 before 2: (b7) r8 = 0 regs=40 stack=0 before 1: (b7) r7 = 0 regs=40 stack=0 before 0: (b7) r6 = 1024 11: R6=scalar(umax=18446744071562067968) R9=-2147483648 11: (b7) r0 = 0 ; R0_w=0 12: (63) *(u32 *)(r10 -4) = r0 last_idx 12 first_idx 11 regs=1 stack=0 before 11: (b7) r0 = 0 13: R0_w=0 R10=fp0 fp-8=0000???? 13: (18) r4 = 0xffff9290dc5bfe00 ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 15: (bf) r1 = r4 ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0) 16: (bf) r2 = r10 ; R2_w=fp0 R10=fp0 17: (07) r2 += -4 ; R2_w=fp-4 18: (85) call bpf_map_lookup_elem#1 ; R0_w=map_value_or_null(id=3,off=0,ks=4,vs=48,imm=0) 19: (55) if r0 != 0x0 goto pc+1 ; R0_w=0 20: (95) exit from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=scalar(umax=18446744071562067968) R7=0 R8=0 R9=-2147483648 R10=fp0 fp-8=mmmm???? 21: (77) r6 >>= 10 ; R6_w=scalar(umax=18014398507384832,var_off=(0x0; 0x3fffffffffffff)) 22: (27) r6 *= 8192 ; R6_w=scalar(smax=9223372036854767616,umax=18446744073709543424,var_off=(0x0; 0xffffffffffffe000),s32_max=2147475456,u32_max=-8192) 23: (bf) r1 = r0 ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0) 24: (0f) r0 += r6 last_idx 24 first_idx 21 regs=40 stack=0 before 23: (bf) r1 = r0 regs=40 stack=0 before 22: (27) r6 *= 8192 regs=40 stack=0 before 21: (77) r6 >>= 10 parent didn't have regs=40 stack=0 marks: R0_rw=map_value(off=0,ks=4,vs=48,imm=0) R6_r=Pscalar(umax=18446744071562067968) R7=0 R8=0 R9=-2147483648 R10=fp0 fp-8=mmmm???? last_idx 19 first_idx 11 regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1 regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1 regs=40 stack=0 before 17: (07) r2 += -4 regs=40 stack=0 before 16: (bf) r2 = r10 regs=40 stack=0 before 15: (bf) r1 = r4 regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00 regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0 regs=40 stack=0 before 11: (b7) r0 = 0 parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar(umax=18446744071562067968) R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0 last_idx 9 first_idx 0 regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1 regs=240 stack=0 before 6: (bd) if r6 <= r9 goto pc+2 regs=240 stack=0 before 5: (05) goto pc+0 regs=240 stack=0 before 4: (97) r6 %= 1025 regs=240 stack=0 before 3: (b7) r9 = -2147483648 regs=40 stack=0 before 2: (b7) r8 = 0 regs=40 stack=0 before 1: (b7) r7 = 0 regs=40 stack=0 before 0: (b7) r6 = 1024 math between map_value pointer and register with unbounded min value is not allowed verification time 886 usec stack depth 4 processed 49 insns (limit 1000000) max_states_per_insn 1 total_states 5 peak_states 5 mark_read 2 Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking") Reported-by: Juan Jose Lopez Jaimez <jjlopezjaimez@google.com> Reported-by: Meador Inge <meadori@google.com> Reported-by: Simon Scannell <simonscannell@google.com> Reported-by: Nenad Stojanovski <thenenadx@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Co-developed-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Reviewed-by: Juan Jose Lopez Jaimez <jjlopezjaimez@google.com> Reviewed-by: Meador Inge <meadori@google.com> Reviewed-by: Simon Scannell <simonscannell@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 71b547f561247897a0a14f3082730156c0533fed ]

Juan Jose et al reported an issue found via fuzzing where the verifier's
pruning logic prematurely marks a program path as safe.

Consider the following program:

   0: (b7) r6 = 1024
   1: (b7) r7 = 0
   2: (b7) r8 = 0
   3: (b7) r9 = -2147483648
   4: (97) r6 %= 1025
   5: (05) goto pc+0
   6: (bd) if r6 <= r9 goto pc+2
   7: (97) r6 %= 1
   8: (b7) r9 = 0
   9: (bd) if r6 <= r9 goto pc+1
  10: (b7) r6 = 0
  11: (b7) r0 = 0
  12: (63) *(u32 *)(r10 -4) = r0
  13: (18) r4 = 0xffff888103693400 // map_ptr(ks=4,vs=48)
  15: (bf) r1 = r4
  16: (bf) r2 = r10
  17: (07) r2 += -4
  18: (85) call bpf_map_lookup_elem#1
  19: (55) if r0 != 0x0 goto pc+1
  20: (95) exit
  21: (77) r6 >>= 10
  22: (27) r6 *= 8192
  23: (bf) r1 = r0
  24: (0f) r0 += r6
  25: (79) r3 = *(u64 *)(r0 +0)
  26: (7b) *(u64 *)(r1 +0) = r3
  27: (95) exit

The verifier treats this as safe, leading to oob read/write access due
to an incorrect verifier conclusion:

  func#0 @0
  0: R1=ctx(off=0,imm=0) R10=fp0
  0: (b7) r6 = 1024                     ; R6_w=1024
  1: (b7) r7 = 0                        ; R7_w=0
  2: (b7) r8 = 0                        ; R8_w=0
  3: (b7) r9 = -2147483648              ; R9_w=-2147483648
  4: (97) r6 %= 1025                    ; R6_w=scalar()
  5: (05) goto pc+0
  6: (bd) if r6 <= r9 goto pc+2         ; R6_w=scalar(umin=18446744071562067969,var_off=(0xffffffff00000000; 0xffffffff)) R9_w=-2147483648
  7: (97) r6 %= 1                       ; R6_w=scalar()
  8: (b7) r9 = 0                        ; R9=0
  9: (bd) if r6 <= r9 goto pc+1         ; R6=scalar(umin=1) R9=0
  10: (b7) r6 = 0                       ; R6_w=0
  11: (b7) r0 = 0                       ; R0_w=0
  12: (63) *(u32 *)(r10 -4) = r0
  last_idx 12 first_idx 9
  regs=1 stack=0 before 11: (b7) r0 = 0
  13: R0_w=0 R10=fp0 fp-8=0000????
  13: (18) r4 = 0xffff8ad3886c2a00      ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  15: (bf) r1 = r4                      ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  16: (bf) r2 = r10                     ; R2_w=fp0 R10=fp0
  17: (07) r2 += -4                     ; R2_w=fp-4
  18: (85) call bpf_map_lookup_elem#1   ; R0=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0)
  19: (55) if r0 != 0x0 goto pc+1       ; R0=0
  20: (95) exit

  from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm????
  21: (77) r6 >>= 10                    ; R6_w=0
  22: (27) r6 *= 8192                   ; R6_w=0
  23: (bf) r1 = r0                      ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0)
  24: (0f) r0 += r6
  last_idx 24 first_idx 19
  regs=40 stack=0 before 23: (bf) r1 = r0
  regs=40 stack=0 before 22: (27) r6 *= 8192
  regs=40 stack=0 before 21: (77) r6 >>= 10
  regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1
  parent didn't have regs=40 stack=0 marks: R0_rw=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0) R6_rw=P0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm????
  last_idx 18 first_idx 9
  regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
  regs=40 stack=0 before 17: (07) r2 += -4
  regs=40 stack=0 before 16: (bf) r2 = r10
  regs=40 stack=0 before 15: (bf) r1 = r4
  regs=40 stack=0 before 13: (18) r4 = 0xffff8ad3886c2a00
  regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
  regs=40 stack=0 before 11: (b7) r0 = 0
  regs=40 stack=0 before 10: (b7) r6 = 0
  25: (79) r3 = *(u64 *)(r0 +0)         ; R0_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar()
  26: (7b) *(u64 *)(r1 +0) = r3         ; R1_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar()
  27: (95) exit

  from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0
  11: (b7) r0 = 0                       ; R0_w=0
  12: (63) *(u32 *)(r10 -4) = r0
  last_idx 12 first_idx 11
  regs=1 stack=0 before 11: (b7) r0 = 0
  13: R0_w=0 R10=fp0 fp-8=0000????
  13: (18) r4 = 0xffff8ad3886c2a00      ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  15: (bf) r1 = r4                      ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  16: (bf) r2 = r10                     ; R2_w=fp0 R10=fp0
  17: (07) r2 += -4                     ; R2_w=fp-4
  18: (85) call bpf_map_lookup_elem#1
  frame 0: propagating r6
  last_idx 19 first_idx 11
  regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
  regs=40 stack=0 before 17: (07) r2 += -4
  regs=40 stack=0 before 16: (bf) r2 = r10
  regs=40 stack=0 before 15: (bf) r1 = r4
  regs=40 stack=0 before 13: (18) r4 = 0xffff8ad3886c2a00
  regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
  regs=40 stack=0 before 11: (b7) r0 = 0
  parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_r=P0 R7=0 R8=0 R9=0 R10=fp0
  last_idx 9 first_idx 9
  regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1
  parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar() R7_w=0 R8_w=0 R9_rw=0 R10=fp0
  last_idx 8 first_idx 0
  regs=40 stack=0 before 8: (b7) r9 = 0
  regs=40 stack=0 before 7: (97) r6 %= 1
  regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
  regs=40 stack=0 before 5: (05) goto pc+0
  regs=40 stack=0 before 4: (97) r6 %= 1025
  regs=40 stack=0 before 3: (b7) r9 = -2147483648
  regs=40 stack=0 before 2: (b7) r8 = 0
  regs=40 stack=0 before 1: (b7) r7 = 0
  regs=40 stack=0 before 0: (b7) r6 = 1024
  19: safe
  frame 0: propagating r6
  last_idx 9 first_idx 0
  regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
  regs=40 stack=0 before 5: (05) goto pc+0
  regs=40 stack=0 before 4: (97) r6 %= 1025
  regs=40 stack=0 before 3: (b7) r9 = -2147483648
  regs=40 stack=0 before 2: (b7) r8 = 0
  regs=40 stack=0 before 1: (b7) r7 = 0
  regs=40 stack=0 before 0: (b7) r6 = 1024

  from 6 to 9: safe
  verification time 110 usec
  stack depth 4
  processed 36 insns (limit 1000000) max_states_per_insn 0 total_states 3 peak_states 3 mark_read 2

The verifier considers this program as safe by mistakenly pruning unsafe
code paths. In the above func#0, code lines 0-10 are of interest. In line
0-3 registers r6 to r9 are initialized with known scalar values. In line 4
the register r6 is reset to an unknown scalar given the verifier does not
track modulo operations. Due to this, the verifier can also not determine
precisely which branches in line 6 and 9 are taken, therefore it needs to
explore them both.

As can be seen, the verifier starts with exploring the false/fall-through
paths first. The 'from 19 to 21' path has both r6=0 and r9=0 and the pointer
arithmetic on r0 += r6 is therefore considered safe. Given the arithmetic,
r6 is correctly marked for precision tracking where backtracking kicks in
where it walks back the current path all the way where r6 was set to 0 in
the fall-through branch.

Next, the pruning logics pops the path 'from 9 to 11' from the stack. Also
here, the state of the registers is the same, that is, r6=0 and r9=0, so
that at line 19 the path can be pruned as it is considered safe. It is
interesting to note that the conditional in line 9 turned r6 into a more
precise state, that is, in the fall-through path at the beginning of line
10, it is R6=scalar(umin=1), and in the branch-taken path (which is analyzed
here) at the beginning of line 11, r6 turned into a known const r6=0 as
r9=0 prior to that and therefore (unsigned) r6 <= 0 concludes that r6 must
be 0 (**):

  [...]                                 ; R6_w=scalar()
  9: (bd) if r6 <= r9 goto pc+1         ; R6=scalar(umin=1) R9=0
  [...]

  from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0
  [...]

The next path is 'from 6 to 9'. The verifier considers the old and current
state equivalent, and therefore prunes the search incorrectly. Looking into
the two states which are being compared by the pruning logic at line 9, the
old state consists of R6_rwD=Pscalar() R9_rwD=0 R10=fp0 and the new state
consists of R1=ctx(off=0,imm=0) R6_w=scalar(umax=18446744071562067968)
R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0. While r6 had the reg->precise flag
correctly set in the old state, r9 did not. Both r6'es are considered as
equivalent given the old one is a superset of the current, more precise one,
however, r9's actual values (0 vs 0x80000000) mismatch. Given the old r9
did not have reg->precise flag set, the verifier does not consider the
register as contributing to the precision state of r6, and therefore it
considered both r9 states as equivalent. However, for this specific pruned
path (which is also the actual path taken at runtime), register r6 will be
0x400 and r9 0x80000000 when reaching line 21, thus oob-accessing the map.

The purpose of precision tracking is to initially mark registers (including
spilled ones) as imprecise to help verifier's pruning logic finding equivalent
states it can then prune if they don't contribute to the program's safety
aspects. For example, if registers are used for pointer arithmetic or to pass
constant length to a helper, then the verifier sets reg->precise flag and
backtracks the BPF program instruction sequence and chain of verifier states
to ensure that the given register or stack slot including their dependencies
are marked as precisely tracked scalar. This also includes any other registers
and slots that contribute to a tracked state of given registers/stack slot.
This backtracking relies on recorded jmp_history and is able to traverse
entire chain of parent states. This process ends only when all the necessary
registers/slots and their transitive dependencies are marked as precise.

The backtrack_insn() is called from the current instruction up to the first
instruction, and its purpose is to compute a bitmask of registers and stack
slots that need precision tracking in the parent's verifier state. For example,
if a current instruction is r6 = r7, then r6 needs precision after this
instruction and r7 needs precision before this instruction, that is, in the
parent state. Hence for the latter r7 is marked and r6 unmarked.

For the class of jmp/jmp32 instructions, backtrack_insn() today only looks
at call and exit instructions and for all other conditionals the masks
remain as-is. However, in the given situation register r6 has a dependency
on r9 (as described above in **), so also that one needs to be marked for
precision tracking. In other words, if an imprecise register influences a
precise one, then the imprecise register should also be marked precise.
Meaning, in the parent state both dest and src register need to be tracked
for precision and therefore the marking must be more conservative by setting
reg->precise flag for both. The precision propagation needs to cover both
for the conditional: if the src reg was marked but not the dst reg and vice
versa.

After the fix the program is correctly rejected:

  func#0 @0
  0: R1=ctx(off=0,imm=0) R10=fp0
  0: (b7) r6 = 1024                     ; R6_w=1024
  1: (b7) r7 = 0                        ; R7_w=0
  2: (b7) r8 = 0                        ; R8_w=0
  3: (b7) r9 = -2147483648              ; R9_w=-2147483648
  4: (97) r6 %= 1025                    ; R6_w=scalar()
  5: (05) goto pc+0
  6: (bd) if r6 <= r9 goto pc+2         ; R6_w=scalar(umin=18446744071562067969,var_off=(0xffffffff80000000; 0x7fffffff),u32_min=-2147483648) R9_w=-2147483648
  7: (97) r6 %= 1                       ; R6_w=scalar()
  8: (b7) r9 = 0                        ; R9=0
  9: (bd) if r6 <= r9 goto pc+1         ; R6=scalar(umin=1) R9=0
  10: (b7) r6 = 0                       ; R6_w=0
  11: (b7) r0 = 0                       ; R0_w=0
  12: (63) *(u32 *)(r10 -4) = r0
  last_idx 12 first_idx 9
  regs=1 stack=0 before 11: (b7) r0 = 0
  13: R0_w=0 R10=fp0 fp-8=0000????
  13: (18) r4 = 0xffff9290dc5bfe00      ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  15: (bf) r1 = r4                      ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  16: (bf) r2 = r10                     ; R2_w=fp0 R10=fp0
  17: (07) r2 += -4                     ; R2_w=fp-4
  18: (85) call bpf_map_lookup_elem#1   ; R0=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0)
  19: (55) if r0 != 0x0 goto pc+1       ; R0=0
  20: (95) exit

  from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm????
  21: (77) r6 >>= 10                    ; R6_w=0
  22: (27) r6 *= 8192                   ; R6_w=0
  23: (bf) r1 = r0                      ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0)
  24: (0f) r0 += r6
  last_idx 24 first_idx 19
  regs=40 stack=0 before 23: (bf) r1 = r0
  regs=40 stack=0 before 22: (27) r6 *= 8192
  regs=40 stack=0 before 21: (77) r6 >>= 10
  regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1
  parent didn't have regs=40 stack=0 marks: R0_rw=map_value_or_null(id=1,off=0,ks=4,vs=48,imm=0) R6_rw=P0 R7=0 R8=0 R9=0 R10=fp0 fp-8=mmmm????
  last_idx 18 first_idx 9
  regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
  regs=40 stack=0 before 17: (07) r2 += -4
  regs=40 stack=0 before 16: (bf) r2 = r10
  regs=40 stack=0 before 15: (bf) r1 = r4
  regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00
  regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
  regs=40 stack=0 before 11: (b7) r0 = 0
  regs=40 stack=0 before 10: (b7) r6 = 0
  25: (79) r3 = *(u64 *)(r0 +0)         ; R0_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar()
  26: (7b) *(u64 *)(r1 +0) = r3         ; R1_w=map_value(off=0,ks=4,vs=48,imm=0) R3_w=scalar()
  27: (95) exit

  from 9 to 11: R1=ctx(off=0,imm=0) R6=0 R7=0 R8=0 R9=0 R10=fp0
  11: (b7) r0 = 0                       ; R0_w=0
  12: (63) *(u32 *)(r10 -4) = r0
  last_idx 12 first_idx 11
  regs=1 stack=0 before 11: (b7) r0 = 0
  13: R0_w=0 R10=fp0 fp-8=0000????
  13: (18) r4 = 0xffff9290dc5bfe00      ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  15: (bf) r1 = r4                      ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  16: (bf) r2 = r10                     ; R2_w=fp0 R10=fp0
  17: (07) r2 += -4                     ; R2_w=fp-4
  18: (85) call bpf_map_lookup_elem#1
  frame 0: propagating r6
  last_idx 19 first_idx 11
  regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
  regs=40 stack=0 before 17: (07) r2 += -4
  regs=40 stack=0 before 16: (bf) r2 = r10
  regs=40 stack=0 before 15: (bf) r1 = r4
  regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00
  regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
  regs=40 stack=0 before 11: (b7) r0 = 0
  parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_r=P0 R7=0 R8=0 R9=0 R10=fp0
  last_idx 9 first_idx 9
  regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1
  parent didn't have regs=240 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar() R7_w=0 R8_w=0 R9_rw=P0 R10=fp0
  last_idx 8 first_idx 0
  regs=240 stack=0 before 8: (b7) r9 = 0
  regs=40 stack=0 before 7: (97) r6 %= 1
  regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
  regs=240 stack=0 before 5: (05) goto pc+0
  regs=240 stack=0 before 4: (97) r6 %= 1025
  regs=240 stack=0 before 3: (b7) r9 = -2147483648
  regs=40 stack=0 before 2: (b7) r8 = 0
  regs=40 stack=0 before 1: (b7) r7 = 0
  regs=40 stack=0 before 0: (b7) r6 = 1024
  19: safe

  from 6 to 9: R1=ctx(off=0,imm=0) R6_w=scalar(umax=18446744071562067968) R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0
  9: (bd) if r6 <= r9 goto pc+1
  last_idx 9 first_idx 0
  regs=40 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
  regs=240 stack=0 before 5: (05) goto pc+0
  regs=240 stack=0 before 4: (97) r6 %= 1025
  regs=240 stack=0 before 3: (b7) r9 = -2147483648
  regs=40 stack=0 before 2: (b7) r8 = 0
  regs=40 stack=0 before 1: (b7) r7 = 0
  regs=40 stack=0 before 0: (b7) r6 = 1024
  last_idx 9 first_idx 0
  regs=200 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
  regs=240 stack=0 before 5: (05) goto pc+0
  regs=240 stack=0 before 4: (97) r6 %= 1025
  regs=240 stack=0 before 3: (b7) r9 = -2147483648
  regs=40 stack=0 before 2: (b7) r8 = 0
  regs=40 stack=0 before 1: (b7) r7 = 0
  regs=40 stack=0 before 0: (b7) r6 = 1024
  11: R6=scalar(umax=18446744071562067968) R9=-2147483648
  11: (b7) r0 = 0                       ; R0_w=0
  12: (63) *(u32 *)(r10 -4) = r0
  last_idx 12 first_idx 11
  regs=1 stack=0 before 11: (b7) r0 = 0
  13: R0_w=0 R10=fp0 fp-8=0000????
  13: (18) r4 = 0xffff9290dc5bfe00      ; R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  15: (bf) r1 = r4                      ; R1_w=map_ptr(off=0,ks=4,vs=48,imm=0) R4_w=map_ptr(off=0,ks=4,vs=48,imm=0)
  16: (bf) r2 = r10                     ; R2_w=fp0 R10=fp0
  17: (07) r2 += -4                     ; R2_w=fp-4
  18: (85) call bpf_map_lookup_elem#1   ; R0_w=map_value_or_null(id=3,off=0,ks=4,vs=48,imm=0)
  19: (55) if r0 != 0x0 goto pc+1       ; R0_w=0
  20: (95) exit

  from 19 to 21: R0=map_value(off=0,ks=4,vs=48,imm=0) R6=scalar(umax=18446744071562067968) R7=0 R8=0 R9=-2147483648 R10=fp0 fp-8=mmmm????
  21: (77) r6 >>= 10                    ; R6_w=scalar(umax=18014398507384832,var_off=(0x0; 0x3fffffffffffff))
  22: (27) r6 *= 8192                   ; R6_w=scalar(smax=9223372036854767616,umax=18446744073709543424,var_off=(0x0; 0xffffffffffffe000),s32_max=2147475456,u32_max=-8192)
  23: (bf) r1 = r0                      ; R0=map_value(off=0,ks=4,vs=48,imm=0) R1_w=map_value(off=0,ks=4,vs=48,imm=0)
  24: (0f) r0 += r6
  last_idx 24 first_idx 21
  regs=40 stack=0 before 23: (bf) r1 = r0
  regs=40 stack=0 before 22: (27) r6 *= 8192
  regs=40 stack=0 before 21: (77) r6 >>= 10
  parent didn't have regs=40 stack=0 marks: R0_rw=map_value(off=0,ks=4,vs=48,imm=0) R6_r=Pscalar(umax=18446744071562067968) R7=0 R8=0 R9=-2147483648 R10=fp0 fp-8=mmmm????
  last_idx 19 first_idx 11
  regs=40 stack=0 before 19: (55) if r0 != 0x0 goto pc+1
  regs=40 stack=0 before 18: (85) call bpf_map_lookup_elem#1
  regs=40 stack=0 before 17: (07) r2 += -4
  regs=40 stack=0 before 16: (bf) r2 = r10
  regs=40 stack=0 before 15: (bf) r1 = r4
  regs=40 stack=0 before 13: (18) r4 = 0xffff9290dc5bfe00
  regs=40 stack=0 before 12: (63) *(u32 *)(r10 -4) = r0
  regs=40 stack=0 before 11: (b7) r0 = 0
  parent didn't have regs=40 stack=0 marks: R1=ctx(off=0,imm=0) R6_rw=Pscalar(umax=18446744071562067968) R7_w=0 R8_w=0 R9_w=-2147483648 R10=fp0
  last_idx 9 first_idx 0
  regs=40 stack=0 before 9: (bd) if r6 <= r9 goto pc+1
  regs=240 stack=0 before 6: (bd) if r6 <= r9 goto pc+2
  regs=240 stack=0 before 5: (05) goto pc+0
  regs=240 stack=0 before 4: (97) r6 %= 1025
  regs=240 stack=0 before 3: (b7) r9 = -2147483648
  regs=40 stack=0 before 2: (b7) r8 = 0
  regs=40 stack=0 before 1: (b7) r7 = 0
  regs=40 stack=0 before 0: (b7) r6 = 1024
  math between map_value pointer and register with unbounded min value is not allowed
  verification time 886 usec
  stack depth 4
  processed 49 insns (limit 1000000) max_states_per_insn 1 total_states 5 peak_states 5 mark_read 2

Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking")
Reported-by: Juan Jose Lopez Jaimez <jjlopezjaimez@google.com>
Reported-by: Meador Inge <meadori@google.com>
Reported-by: Simon Scannell <simonscannell@google.com>
Reported-by: Nenad Stojanovski <thenenadx@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Co-developed-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Reviewed-by: Juan Jose Lopez Jaimez <jjlopezjaimez@google.com>
Reviewed-by: Meador Inge <meadori@google.com>
Reviewed-by: Simon Scannell <simonscannell@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
sched/fair: Fix imbalance overflow 2023-04-20T10:37:00+00:00 Vincent Guittot vincent.guittot@linaro.org 2023-04-11T09:06:11+00:00 273727f22f62d77e930f5fd069db48c7198b8f6c [ Upstream commit 91dcf1e8068e9a8823e419a7a34ff4341275fb70 ] When local group is fully busy but its average load is above system load, computing the imbalance will overflow and local group is not the best target for pulling this load. Fixes: 0b0695f2b34a ("sched/fair: Rework load_balance()") Reported-by: Tingjia Cao <tjcao980311@gmail.com> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Tingjia Cao <tjcao980311@gmail.com> Link: https://lore.kernel.org/lkml/CABcWv9_DAhVBOq2=W=2ypKE9dKM5s2DvoV8-U0+GDwwuKZ89jQ@mail.gmail.com/T/ Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 91dcf1e8068e9a8823e419a7a34ff4341275fb70 ]

When local group is fully busy but its average load is above system load,
computing the imbalance will overflow and local group is not the best
target for pulling this load.

Fixes: 0b0695f2b34a ("sched/fair: Rework load_balance()")
Reported-by: Tingjia Cao <tjcao980311@gmail.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tingjia Cao <tjcao980311@gmail.com>
Link: https://lore.kernel.org/lkml/CABcWv9_DAhVBOq2=W=2ypKE9dKM5s2DvoV8-U0+GDwwuKZ89jQ@mail.gmail.com/T/
Signed-off-by: Sasha Levin <sashal@kernel.org>
cgroup/cpuset: Add cpuset_can_fork() and cpuset_cancel_fork() methods 2023-04-20T10:36:59+00:00 Waiman Long longman@redhat.com 2023-04-11T13:35:59+00:00 89c98802f0b754f3ee130480509f088be1daf81c commit eee87853794187f6adbe19533ed79c8b44b36a91 upstream. In the case of CLONE_INTO_CGROUP, not all cpusets are ready to accept new tasks. It is too late to check that in cpuset_fork(). So we need to add the cpuset_can_fork() and cpuset_cancel_fork() methods to pre-check it before we can allow attachment to a different cpuset. We also need to set the attach_in_progress flag to alert other code that a new task is going to be added to the cpuset. Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups") Suggested-by: Michal Koutný <mkoutny@suse.com> Signed-off-by: Waiman Long <longman@redhat.com> Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit eee87853794187f6adbe19533ed79c8b44b36a91 upstream.

In the case of CLONE_INTO_CGROUP, not all cpusets are ready to accept
new tasks. It is too late to check that in cpuset_fork(). So we need
to add the cpuset_can_fork() and cpuset_cancel_fork() methods to
pre-check it before we can allow attachment to a different cpuset.

We also need to set the attach_in_progress flag to alert other code
that a new task is going to be added to the cpuset.

Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups")
Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cgroup/cpuset: Make cpuset_fork() handle CLONE_INTO_CGROUP properly 2023-04-20T10:36:59+00:00 Waiman Long longman@redhat.com 2023-04-11T13:35:58+00:00 1eeb31c3ac1a79eae566c763bd21237bc5d39198 commit 42a11bf5c5436e91b040aeb04063be1710bb9f9c upstream. By default, the clone(2) syscall spawn a child process into the same cgroup as its parent. With the use of the CLONE_INTO_CGROUP flag introduced by commit ef2c41cf38a7 ("clone3: allow spawning processes into cgroups"), the child will be spawned into a different cgroup which is somewhat similar to writing the child's tid into "cgroup.threads". The current cpuset_fork() method does not properly handle the CLONE_INTO_CGROUP case where the cpuset of the child may be different from that of its parent. Update the cpuset_fork() method to treat the CLONE_INTO_CGROUP case similar to cpuset_attach(). Since the newly cloned task has not been running yet, its actual memory usage isn't known. So it is not necessary to make change to mm in cpuset_fork(). Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups") Reported-by: Giuseppe Scrivano <gscrivan@redhat.com> Signed-off-by: Waiman Long <longman@redhat.com> Cc: stable@vger.kernel.org # v5.7+ Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 42a11bf5c5436e91b040aeb04063be1710bb9f9c upstream.

By default, the clone(2) syscall spawn a child process into the same
cgroup as its parent. With the use of the CLONE_INTO_CGROUP flag
introduced by commit ef2c41cf38a7 ("clone3: allow spawning processes
into cgroups"), the child will be spawned into a different cgroup which
is somewhat similar to writing the child's tid into "cgroup.threads".

The current cpuset_fork() method does not properly handle the
CLONE_INTO_CGROUP case where the cpuset of the child may be different
from that of its parent.  Update the cpuset_fork() method to treat the
CLONE_INTO_CGROUP case similar to cpuset_attach().

Since the newly cloned task has not been running yet, its actual
memory usage isn't known. So it is not necessary to make change to mm
in cpuset_fork().

Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups")
Reported-by: Giuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cgroup/cpuset: Wake up cpuset_attach_wq tasks in cpuset_cancel_attach() 2023-04-20T10:36:59+00:00 Waiman Long longman@redhat.com 2023-04-11T13:35:57+00:00 6aa942500458a39afb02d10d20d2ed59349ab2a4 commit ba9182a89626d5f83c2ee4594f55cb9c1e60f0e2 upstream. After a successful cpuset_can_attach() call which increments the attach_in_progress flag, either cpuset_cancel_attach() or cpuset_attach() will be called later. In cpuset_attach(), tasks in cpuset_attach_wq, if present, will be woken up at the end. That is not the case in cpuset_cancel_attach(). So missed wakeup is possible if the attach operation is somehow cancelled. Fix that by doing the wakeup in cpuset_cancel_attach() as well. Fixes: e44193d39e8d ("cpuset: let hotplug propagation work wait for task attaching") Signed-off-by: Waiman Long <longman@redhat.com> Reviewed-by: Michal Koutný <mkoutny@suse.com> Cc: stable@vger.kernel.org # v3.11+ Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ba9182a89626d5f83c2ee4594f55cb9c1e60f0e2 upstream.

After a successful cpuset_can_attach() call which increments the
attach_in_progress flag, either cpuset_cancel_attach() or cpuset_attach()
will be called later. In cpuset_attach(), tasks in cpuset_attach_wq,
if present, will be woken up at the end. That is not the case in
cpuset_cancel_attach(). So missed wakeup is possible if the attach
operation is somehow cancelled. Fix that by doing the wakeup in
cpuset_cancel_attach() as well.

Fixes: e44193d39e8d ("cpuset: let hotplug propagation work wait for task attaching")
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Cc: stable@vger.kernel.org # v3.11+
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cgroup/cpuset: Fix partition root's cpuset.cpus update bug 2023-04-20T10:36:59+00:00 Waiman Long longman@redhat.com 2023-03-17T15:15:05+00:00 37d82023df0464e46a73d92ce5dc6fdf09b9313d commit 292fd843de26c551856e66faf134512c52dd78b4 upstream. It was found that commit 7a2127e66a00 ("cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task") introduced a bug that corrupted "cpuset.cpus" of a partition root when it was updated. It is because the tmp->new_cpus field of the passed tmp parameter of update_parent_subparts_cpumask() should not be used at all as it contains important cpumask data that should not be overwritten. Fix it by using tmp->addmask instead. Also update update_cpumask() to make sure that trialcs->cpu_allowed will not be corrupted until it is no longer needed. Fixes: 7a2127e66a00 ("cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task") Signed-off-by: Waiman Long <longman@redhat.com> Cc: stable@vger.kernel.org # v6.2+ Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 292fd843de26c551856e66faf134512c52dd78b4 upstream.

It was found that commit 7a2127e66a00 ("cpuset: Call
set_cpus_allowed_ptr() with appropriate mask for task") introduced a bug
that corrupted "cpuset.cpus" of a partition root when it was updated.

It is because the tmp->new_cpus field of the passed tmp parameter
of update_parent_subparts_cpumask() should not be used at all as
it contains important cpumask data that should not be overwritten.
Fix it by using tmp->addmask instead.

Also update update_cpumask() to make sure that trialcs->cpu_allowed
will not be corrupted until it is no longer needed.

Fixes: 7a2127e66a00 ("cpuset: Call set_cpus_allowed_ptr() with appropriate mask for task")
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v6.2+
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cgroup: fix display of forceidle time at root 2023-04-20T10:36:59+00:00 Josh Don joshdon@google.com 2023-03-15T21:40:29+00:00 daea92f089485d04e6a2fe35e2f89e4369232039 commit fcdb1eda5302599045bb366e679cccb4216f3873 upstream. We need to reset forceidle_sum to 0 when reading from root, since the bstat we accumulate into is stack allocated. To make this more robust, just replace the existing cputime reset with a memset of the overall bstat. Signed-off-by: Josh Don <joshdon@google.com> Fixes: 1fcf54deb767 ("sched/core: add forced idle accounting for cgroups") Cc: stable@vger.kernel.org # v6.0+ Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit fcdb1eda5302599045bb366e679cccb4216f3873 upstream.

We need to reset forceidle_sum to 0 when reading from root, since the
bstat we accumulate into is stack allocated.

To make this more robust, just replace the existing cputime reset with a
memset of the overall bstat.

Signed-off-by: Josh Don <joshdon@google.com>
Fixes: 1fcf54deb767 ("sched/core: add forced idle accounting for cgroups")
Cc: stable@vger.kernel.org # v6.0+
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tracing: Have tracing_snapshot_instance_cond() write errors to the appropriate instance 2023-04-20T10:36:58+00:00 Steven Rostedt (Google) rostedt@goodmis.org 2023-04-05T02:21:14+00:00 75f95216cfadb0fb6796b90cf42b9ea076fa0723 [ Upstream commit 9d52727f8043cfda241ae96896628d92fa9c50bb ] If a trace instance has a failure with its snapshot code, the error message is to be written to that instance's buffer. But currently, the message is written to the top level buffer. Worse yet, it may also disable the top level buffer and not the instance that had the issue. Link: https://lkml.kernel.org/r/20230405022341.688730321@goodmis.org Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ross Zwisler <zwisler@google.com> Fixes: 2824f50332486 ("tracing: Make the snapshot trigger work with instances") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 9d52727f8043cfda241ae96896628d92fa9c50bb ]

If a trace instance has a failure with its snapshot code, the error
message is to be written to that instance's buffer. But currently, the
message is written to the top level buffer. Worse yet, it may also disable
the top level buffer and not the instance that had the issue.

Link: https://lkml.kernel.org/r/20230405022341.688730321@goodmis.org

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <zwisler@google.com>
Fixes: 2824f50332486 ("tracing: Make the snapshot trigger work with instances")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>