linux-stable.git/kernel/bpf/verifier.c, branch linux-5.6.y Linux kernel stable tree bpf: Add bpf_probe_read_{user, kernel}_str() to do_refine_retval_range 2020-05-27T15:48:15+00:00 Daniel Borkmann daniel@iogearbox.net 2020-05-15T10:11:17+00:00 830356a694efb6b33253e4ce9de5954a0693057a commit 47cc0ed574abcbbde0cf143ddb21a0baed1aa2df upstream. Given bpf_probe_read{,str}() BPF helpers are now only available under CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE, we need to add the drop-in replacements of bpf_probe_read_{kernel,user}_str() to do_refine_retval_range() as well to avoid hitting the same issue as in 849fa50662fbc ("bpf/verifier: refine retval R0 state for bpf_get_stack helper"). Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200515101118.6508-3-daniel@iogearbox.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 47cc0ed574abcbbde0cf143ddb21a0baed1aa2df upstream.

Given bpf_probe_read{,str}() BPF helpers are now only available under
CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE, we need to add the drop-in
replacements of bpf_probe_read_{kernel,user}_str() to do_refine_retval_range()
as well to avoid hitting the same issue as in 849fa50662fbc ("bpf/verifier:
refine retval R0 state for bpf_get_stack helper").

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200515101118.6508-3-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf: Enforce returning 0 for fentry/fexit progs 2020-05-20T06:22:38+00:00 Yonghong Song yhs@fb.com 2020-05-14T05:32:05+00:00 9afc9ff98658bbe517b9d1ee451bbe8e44897424 commit e92888c72fbdc6f9d07b3b0604c012e81d7c0da7 upstream. Currently, tracing/fentry and tracing/fexit prog return values are not enforced. In trampoline codes, the fentry/fexit prog return values are ignored. Let us enforce it to be 0 to avoid confusion and allows potential future extension. This patch also explicitly added return value checking for tracing/raw_tp, tracing/fmod_ret, and freplace programs such that these program return values can be anything. The purpose are two folds: 1. to make it explicit about return value expectations for these programs in verifier. 2. for tracing prog_type, if a future attach type is added, the default is -ENOTSUPP which will enforce to specify return value ranges explicitly. Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline") Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200514053206.1298415-1-yhs@fb.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e92888c72fbdc6f9d07b3b0604c012e81d7c0da7 upstream.

Currently, tracing/fentry and tracing/fexit prog
return values are not enforced. In trampoline codes,
the fentry/fexit prog return values are ignored.
Let us enforce it to be 0 to avoid confusion and
allows potential future extension.

This patch also explicitly added return value
checking for tracing/raw_tp, tracing/fmod_ret,
and freplace programs such that these program
return values can be anything. The purpose are
two folds:
 1. to make it explicit about return value expectations
    for these programs in verifier.
 2. for tracing prog_type, if a future attach type
    is added, the default is -ENOTSUPP which will
    enforce to specify return value ranges explicitly.

Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200514053206.1298415-1-yhs@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf: Propagate expected_attach_type when verifying freplace programs 2020-05-02T06:50:56+00:00 Toke Høiland-Jørgensen toke@redhat.com 2020-04-24T13:34:27+00:00 cbde2870a193d0a458f30350355694cf45f510b4 commit 03f87c0b45b177ba5f6b4a9bbe9f95e4aba31026 upstream. For some program types, the verifier relies on the expected_attach_type of the program being verified in the verification process. However, for freplace programs, the attach type was not propagated along with the verifier ops, so the expected_attach_type would always be zero for freplace programs. This in turn caused the verifier to sometimes make the wrong call for freplace programs. For all existing uses of expected_attach_type for this purpose, the result of this was only false negatives (i.e., freplace functions would be rejected by the verifier even though they were valid programs for the target they were replacing). However, should a false positive be introduced, this can lead to out-of-bounds accesses and/or crashes. The fix introduced in this patch is to propagate the expected_attach_type to the freplace program during verification, and reset it after that is done. Fixes: be8704ff07d2 ("bpf: Introduce dynamic program extensions") Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158773526726.293902.13257293296560360508.stgit@toke.dk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 03f87c0b45b177ba5f6b4a9bbe9f95e4aba31026 upstream.

For some program types, the verifier relies on the expected_attach_type of
the program being verified in the verification process. However, for
freplace programs, the attach type was not propagated along with the
verifier ops, so the expected_attach_type would always be zero for freplace
programs.

This in turn caused the verifier to sometimes make the wrong call for
freplace programs. For all existing uses of expected_attach_type for this
purpose, the result of this was only false negatives (i.e., freplace
functions would be rejected by the verifier even though they were valid
programs for the target they were replacing). However, should a false
positive be introduced, this can lead to out-of-bounds accesses and/or
crashes.

The fix introduced in this patch is to propagate the expected_attach_type
to the freplace program during verification, and reset it after that is
done.

Fixes: be8704ff07d2 ("bpf: Introduce dynamic program extensions")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158773526726.293902.13257293296560360508.stgit@toke.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf: Fix handling of XADD on BTF memory 2020-05-02T06:50:54+00:00 Jann Horn jannh@google.com 2020-04-17T00:00:07+00:00 7cc3a7ff2658e8aadfa4656e09d7df153acf4a95 commit 8ff3571f7e1bf3f293cc5e3dc14f2943f4fa7fcf upstream. check_xadd() can cause check_ptr_to_btf_access() to be executed with atype==BPF_READ and value_regno==-1 (meaning "just check whether the access is okay, don't tell me what type it will result in"). Handle that case properly and skip writing type information, instead of indexing into the registers at index -1 and writing into out-of-bounds memory. Note that at least at the moment, you can't actually write through a BTF pointer, so check_xadd() will reject the program after calling check_ptr_to_btf_access with atype==BPF_WRITE; but that's after the verifier has already corrupted memory. This patch assumes that BTF pointers are not available in unprivileged programs. Fixes: 9e15db66136a ("bpf: Implement accurate raw_tp context access via BTF") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200417000007.10734-2-jannh@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 8ff3571f7e1bf3f293cc5e3dc14f2943f4fa7fcf upstream.

check_xadd() can cause check_ptr_to_btf_access() to be executed with
atype==BPF_READ and value_regno==-1 (meaning "just check whether the access
is okay, don't tell me what type it will result in").
Handle that case properly and skip writing type information, instead of
indexing into the registers at index -1 and writing into out-of-bounds
memory.

Note that at least at the moment, you can't actually write through a BTF
pointer, so check_xadd() will reject the program after calling
check_ptr_to_btf_access with atype==BPF_WRITE; but that's after the
verifier has already corrupted memory.

This patch assumes that BTF pointers are not available in unprivileged
programs.

Fixes: 9e15db66136a ("bpf: Implement accurate raw_tp context access via BTF")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200417000007.10734-2-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf: Forbid XADD on spilled pointers for unprivileged users 2020-05-02T06:50:46+00:00 Jann Horn jannh@google.com 2020-04-17T00:00:06+00:00 3bbd5b9cf3f03722d7d138916db43ab092435bd6 commit 6e7e63cbb023976d828cdb22422606bf77baa8a9 upstream. When check_xadd() verifies an XADD operation on a pointer to a stack slot containing a spilled pointer, check_stack_read() verifies that the read, which is part of XADD, is valid. However, since the placeholder value -1 is passed as `value_regno`, check_stack_read() can only return a binary decision and can't return the type of the value that was read. The intent here is to verify whether the value read from the stack slot may be used as a SCALAR_VALUE; but since check_stack_read() doesn't check the type, and the type information is lost when check_stack_read() returns, this is not enforced, and a malicious user can abuse XADD to leak spilled kernel pointers. Fix it by letting check_stack_read() verify that the value is usable as a SCALAR_VALUE if no type information is passed to the caller. To be able to use __is_pointer_value() in check_stack_read(), move it up. Fix up the expected unprivileged error message for a BPF selftest that, until now, assumed that unprivileged users can use XADD on stack-spilled pointers. This also gives us a test for the behavior introduced in this patch for free. In theory, this could also be fixed by forbidding XADD on stack spills entirely, since XADD is a locked operation (for operations on memory with concurrency) and there can't be any concurrency on the BPF stack; but Alexei has said that he wants to keep XADD on stack slots working to avoid changes to the test suite [1]. The following BPF program demonstrates how to leak a BPF map pointer as an unprivileged user using this bug: // r7 = map_pointer BPF_LD_MAP_FD(BPF_REG_7, small_map), // r8 = launder(map_pointer) BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_7, -8), BPF_MOV64_IMM(BPF_REG_1, 0), ((struct bpf_insn) { .code = BPF_STX | BPF_DW | BPF_XADD, .dst_reg = BPF_REG_FP, .src_reg = BPF_REG_1, .off = -8 }), BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_FP, -8), // store r8 into map BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_7), BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP), BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -4), BPF_ST_MEM(BPF_W, BPF_REG_ARG2, 0, 0), BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1), BPF_EXIT_INSN(), BPF_STX_MEM(BPF_DW, BPF_REG_0, BPF_REG_8, 0), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN() [1] https://lore.kernel.org/bpf/20200416211116.qxqcza5vo2ddnkdq@ast-mbp.dhcp.thefacebook.com/ Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200417000007.10734-1-jannh@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 6e7e63cbb023976d828cdb22422606bf77baa8a9 upstream.

When check_xadd() verifies an XADD operation on a pointer to a stack slot
containing a spilled pointer, check_stack_read() verifies that the read,
which is part of XADD, is valid. However, since the placeholder value -1 is
passed as `value_regno`, check_stack_read() can only return a binary
decision and can't return the type of the value that was read. The intent
here is to verify whether the value read from the stack slot may be used as
a SCALAR_VALUE; but since check_stack_read() doesn't check the type, and
the type information is lost when check_stack_read() returns, this is not
enforced, and a malicious user can abuse XADD to leak spilled kernel
pointers.

Fix it by letting check_stack_read() verify that the value is usable as a
SCALAR_VALUE if no type information is passed to the caller.

To be able to use __is_pointer_value() in check_stack_read(), move it up.

Fix up the expected unprivileged error message for a BPF selftest that,
until now, assumed that unprivileged users can use XADD on stack-spilled
pointers. This also gives us a test for the behavior introduced in this
patch for free.

In theory, this could also be fixed by forbidding XADD on stack spills
entirely, since XADD is a locked operation (for operations on memory with
concurrency) and there can't be any concurrency on the BPF stack; but
Alexei has said that he wants to keep XADD on stack slots working to avoid
changes to the test suite [1].

The following BPF program demonstrates how to leak a BPF map pointer as an
unprivileged user using this bug:

    // r7 = map_pointer
    BPF_LD_MAP_FD(BPF_REG_7, small_map),
    // r8 = launder(map_pointer)
    BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_7, -8),
    BPF_MOV64_IMM(BPF_REG_1, 0),
    ((struct bpf_insn) {
      .code  = BPF_STX | BPF_DW | BPF_XADD,
      .dst_reg = BPF_REG_FP,
      .src_reg = BPF_REG_1,
      .off = -8
    }),
    BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_FP, -8),

    // store r8 into map
    BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_7),
    BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP),
    BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -4),
    BPF_ST_MEM(BPF_W, BPF_REG_ARG2, 0, 0),
    BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
    BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
    BPF_EXIT_INSN(),
    BPF_STX_MEM(BPF_DW, BPF_REG_0, BPF_REG_8, 0),

    BPF_MOV64_IMM(BPF_REG_0, 0),
    BPF_EXIT_INSN()

[1] https://lore.kernel.org/bpf/20200416211116.qxqcza5vo2ddnkdq@ast-mbp.dhcp.thefacebook.com/

Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200417000007.10734-1-jannh@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf: fix buggy r0 retval refinement for tracing helpers 2020-04-23T08:38:26+00:00 Daniel Borkmann daniel@iogearbox.net 2020-04-21T13:01:49+00:00 311e070b089c2885b81450bd45764f7331b2809b [ no upstream commit ] See the glory details in 100605035e15 ("bpf: Verifier, do_refine_retval_range may clamp umin to 0 incorrectly") for why 849fa50662fb ("bpf/verifier: refine retval R0 state for bpf_get_stack helper") is buggy. The whole series however is not suitable for stable since it adds significant amount [0] of verifier complexity in order to add 32bit subreg tracking. Something simpler is needed. Unfortunately, reverting 849fa50662fb ("bpf/verifier: refine retval R0 state for bpf_get_stack helper") or just cherry-picking 100605035e15 ("bpf: Verifier, do_refine_retval_range may clamp umin to 0 incorrectly") is not an option since it will break existing tracing programs badly (at least those that are using bpf_get_stack() and bpf_probe_read_str() helpers). Not fixing it in stable is also not an option since on 4.19 kernels an error will cause a soft-lockup due to hitting dead-code sanitized branch since we don't hard-wire such branches in old kernels yet. But even then for 5.x 849fa50662fb ("bpf/verifier: refine retval R0 state for bpf_get_stack helper") would cause wrong bounds on the verifier simluation when an error is hit. In one of the earlier iterations of mentioned patch series for upstream there was the concern that just using smax_value in do_refine_retval_range() would nuke bounds by subsequent <<32 >>32 shifts before the comparison against 0 [1] which eventually led to the 32bit subreg tracking in the first place. While I initially went for implementing the idea [1] to pattern match the two shift operations, it turned out to be more complex than actually needed, meaning, we could simply treat do_refine_retval_range() similarly to how we branch off verification for conditionals or under speculation, that is, pushing a new reg state to the stack for later verification. This means, instead of verifying the current path with the ret_reg in [S32MIN, msize_max_value] interval where later bounds would get nuked, we split this into two: i) for the success case where ret_reg can be in [0, msize_max_value], and ii) for the error case with ret_reg known to be in interval [S32MIN, -1]. Latter will preserve the bounds during these shift patterns and can match reg < 0 test. test_progs also succeed with this approach. [0] https://lore.kernel.org/bpf/158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower/ [1] https://lore.kernel.org/bpf/158015334199.28573.4940395881683556537.stgit@john-XPS-13-9370/T/#m2e0ad1d5949131014748b6daa48a3495e7f0456d Fixes: 849fa50662fb ("bpf/verifier: refine retval R0 state for bpf_get_stack helper") Reported-by: Lorenzo Fontana <fontanalorenz@gmail.com> Reported-by: Leonardo Di Donato <leodidonato@gmail.com> Reported-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Tested-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
[ no upstream commit ]

See the glory details in 100605035e15 ("bpf: Verifier, do_refine_retval_range
may clamp umin to 0 incorrectly") for why 849fa50662fb ("bpf/verifier: refine
retval R0 state for bpf_get_stack helper") is buggy. The whole series however
is not suitable for stable since it adds significant amount [0] of verifier
complexity in order to add 32bit subreg tracking. Something simpler is needed.

Unfortunately, reverting 849fa50662fb ("bpf/verifier: refine retval R0 state
for bpf_get_stack helper") or just cherry-picking 100605035e15 ("bpf: Verifier,
do_refine_retval_range may clamp umin to 0 incorrectly") is not an option since
it will break existing tracing programs badly (at least those that are using
bpf_get_stack() and bpf_probe_read_str() helpers). Not fixing it in stable is
also not an option since on 4.19 kernels an error will cause a soft-lockup due
to hitting dead-code sanitized branch since we don't hard-wire such branches
in old kernels yet. But even then for 5.x 849fa50662fb ("bpf/verifier: refine
retval R0 state for bpf_get_stack helper") would cause wrong bounds on the
verifier simluation when an error is hit.

In one of the earlier iterations of mentioned patch series for upstream there
was the concern that just using smax_value in do_refine_retval_range() would
nuke bounds by subsequent <<32 >>32 shifts before the comparison against 0 [1]
which eventually led to the 32bit subreg tracking in the first place. While I
initially went for implementing the idea [1] to pattern match the two shift
operations, it turned out to be more complex than actually needed, meaning, we
could simply treat do_refine_retval_range() similarly to how we branch off
verification for conditionals or under speculation, that is, pushing a new
reg state to the stack for later verification. This means, instead of verifying
the current path with the ret_reg in [S32MIN, msize_max_value] interval where
later bounds would get nuked, we split this into two: i) for the success case
where ret_reg can be in [0, msize_max_value], and ii) for the error case with
ret_reg known to be in interval [S32MIN, -1]. Latter will preserve the bounds
during these shift patterns and can match reg < 0 test. test_progs also succeed
with this approach.

  [0] https://lore.kernel.org/bpf/158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower/
  [1] https://lore.kernel.org/bpf/158015334199.28573.4940395881683556537.stgit@john-XPS-13-9370/T/#m2e0ad1d5949131014748b6daa48a3495e7f0456d

Fixes: 849fa50662fb ("bpf/verifier: refine retval R0 state for bpf_get_stack helper")
Reported-by: Lorenzo Fontana <fontanalorenz@gmail.com>
Reported-by: Leonardo Di Donato <leodidonato@gmail.com>
Reported-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
bpf: Fix tnum constraints for 32-bit comparisons 2020-04-17T14:13:48+00:00 Jann Horn jannh@google.com 2020-03-30T16:03:23+00:00 98666f218f188f9cbd60560cc40eb4c4bdb67c0b [ Upstream commit 604dca5e3af1db98bd123b7bfc02b017af99e3a0 ] The BPF verifier tried to track values based on 32-bit comparisons by (ab)using the tnum state via 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions"). The idea is that after a check like this: if ((u32)r0 > 3) exit We can't meaningfully constrain the arithmetic-range-based tracking, but we can update the tnum state to (value=0,mask=0xffff'ffff'0000'0003). However, the implementation from 581738a681b6 didn't compute the tnum constraint based on the fixed operand, but instead derives it from the arithmetic-range-based tracking. This means that after the following sequence of operations: if (r0 >= 0x1'0000'0001) exit if ((u32)r0 > 7) exit The verifier assumed that the lower half of r0 is in the range (0, 0) and apply the tnum constraint (value=0,mask=0xffff'ffff'0000'0000) thus causing the overall tnum to be (value=0,mask=0x1'0000'0000), which was incorrect. Provide a fixed implementation. Fixes: 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330160324.15259-3-daniel@iogearbox.net Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 604dca5e3af1db98bd123b7bfc02b017af99e3a0 ]

The BPF verifier tried to track values based on 32-bit comparisons by
(ab)using the tnum state via 581738a681b6 ("bpf: Provide better register
bounds after jmp32 instructions"). The idea is that after a check like
this:

    if ((u32)r0 > 3)
      exit

We can't meaningfully constrain the arithmetic-range-based tracking, but
we can update the tnum state to (value=0,mask=0xffff'ffff'0000'0003).
However, the implementation from 581738a681b6 didn't compute the tnum
constraint based on the fixed operand, but instead derives it from the
arithmetic-range-based tracking. This means that after the following
sequence of operations:

    if (r0 >= 0x1'0000'0001)
      exit
    if ((u32)r0 > 7)
      exit

The verifier assumed that the lower half of r0 is in the range (0, 0)
and apply the tnum constraint (value=0,mask=0xffff'ffff'0000'0000) thus
causing the overall tnum to be (value=0,mask=0x1'0000'0000), which was
incorrect. Provide a fixed implementation.

Fixes: 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200330160324.15259-3-daniel@iogearbox.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
bpf: Undo incorrect __reg_bound_offset32 handling 2020-04-01T08:58:10+00:00 Daniel Borkmann daniel@iogearbox.net 2020-03-30T16:03:22+00:00 6797143df51c8ae259aa4bfe4e99c832b20bde8a commit f2d67fec0b43edce8c416101cdc52e71145b5fef upstream. Anatoly has been fuzzing with kBdysch harness and reported a hang in one of the outcomes: 0: (b7) r0 = 808464432 1: (7f) r0 >>= r0 2: (14) w0 -= 808464432 3: (07) r0 += 808464432 4: (b7) r1 = 808464432 5: (de) if w1 s<= w0 goto pc+0 R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020;0x10000001f)) R1_w=invP808464432 R10=fp0 6: (07) r0 += -2144337872 7: (14) w0 -= -1607454672 8: (25) if r0 > 0x30303030 goto pc+0 R0_w=invP(id=0,umin_value=271581184,umax_value=271581311,var_off=(0x10300000;0x7f)) R1_w=invP808464432 R10=fp0 9: (76) if w0 s>= 0x303030 goto pc+2 12: (95) exit from 8 to 9: safe from 5 to 6: R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020;0x10000001f)) R1_w=invP808464432 R10=fp0 6: (07) r0 += -2144337872 7: (14) w0 -= -1607454672 8: (25) if r0 > 0x30303030 goto pc+0 R0_w=invP(id=0,umin_value=271581184,umax_value=271581311,var_off=(0x10300000;0x7f)) R1_w=invP808464432 R10=fp0 9: safe from 8 to 9: safe verification time 589 usec stack depth 0 processed 17 insns (limit 1000000) [...] The underlying program was xlated as follows: # bpftool p d x i 9 0: (b7) r0 = 808464432 1: (7f) r0 >>= r0 2: (14) w0 -= 808464432 3: (07) r0 += 808464432 4: (b7) r1 = 808464432 5: (de) if w1 s<= w0 goto pc+0 6: (07) r0 += -2144337872 7: (14) w0 -= -1607454672 8: (25) if r0 > 0x30303030 goto pc+0 9: (76) if w0 s>= 0x303030 goto pc+2 10: (05) goto pc-1 11: (05) goto pc-1 12: (95) exit The verifier rewrote original instructions it recognized as dead code with 'goto pc-1', but reality differs from verifier simulation in that we're actually able to trigger a hang due to hitting the 'goto pc-1' instructions. Taking different examples to make the issue more obvious: in this example we're probing bounds on a completely unknown scalar variable in r1: [...] 5: R0_w=inv1 R1_w=inv(id=0) R10=fp0 5: (18) r2 = 0x4000000000 7: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R10=fp0 7: (18) r3 = 0x2000000000 9: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R10=fp0 9: (18) r4 = 0x400 11: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R10=fp0 11: (18) r5 = 0x200 13: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0 13: (2d) if r1 > r2 goto pc+4 R0_w=inv1 R1_w=inv(id=0,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0 14: R0_w=inv1 R1_w=inv(id=0,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0 14: (ad) if r1 < r3 goto pc+3 R0_w=inv1 R1_w=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0 15: R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0 15: (2e) if w1 > w4 goto pc+2 R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0 16: R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0 16: (ae) if w1 < w5 goto pc+1 R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0 [...] We're first probing lower/upper bounds via jmp64, later we do a similar check via jmp32 and examine the resulting var_off there. After fall-through in insn 14, we get the following bounded r1 with 0x7fffffffff unknown marked bits in the variable section. Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000: max: 0b100000000000000000000000000000000000000 / 0x4000000000 var: 0b111111111111111111111111111111111111111 / 0x7fffffffff min: 0b010000000000000000000000000000000000000 / 0x2000000000 Now, in insn 15 and 16, we perform a similar probe with lower/upper bounds in jmp32. Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000 and w1 <= 0x400 and w1 >= 0x200: max: 0b100000000000000000000000000000000000000 / 0x4000000000 var: 0b111111100000000000000000000000000000000 / 0x7f00000000 min: 0b010000000000000000000000000000000000000 / 0x2000000000 The lower/upper bounds haven't changed since they have high bits set in u64 space and the jmp32 tests can only refine bounds in the low bits. However, for the var part the expectation would have been 0x7f000007ff or something less precise up to 0x7fffffffff. A outcome of 0x7f00000000 is not correct since it would contradict the earlier probed bounds where we know that the result should have been in [0x200,0x400] in u32 space. Therefore, tests with such info will lead to wrong verifier assumptions later on like falsely predicting conditional jumps to be always taken, etc. The issue here is that __reg_bound_offset32()'s implementation from commit 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions") makes an incorrect range assumption: static void __reg_bound_offset32(struct bpf_reg_state *reg) { u64 mask = 0xffffFFFF; struct tnum range = tnum_range(reg->umin_value & mask, reg->umax_value & mask); struct tnum lo32 = tnum_cast(reg->var_off, 4); struct tnum hi32 = tnum_lshift(tnum_rshift(reg->var_off, 32), 32); reg->var_off = tnum_or(hi32, tnum_intersect(lo32, range)); } In the above walk-through example, __reg_bound_offset32() as-is chose a range after masking with 0xffffffff of [0x0,0x0] since umin:0x2000000000 and umax:0x4000000000 and therefore the lo32 part was clamped to 0x0 as well. However, in the umin:0x2000000000 and umax:0x4000000000 range above we'd end up with an actual possible interval of [0x0,0xffffffff] for u32 space instead. In case of the original reproducer, the situation looked as follows at insn 5 for r0: [...] 5: R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x0; 0x1ffffffff)) R1_w=invP808464432 R10=fp0 0x30303030 0x13030302f 5: (de) if w1 s<= w0 goto pc+0 R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020; 0x10000001f)) R1_w=invP808464432 R10=fp0 0x30303030 0x13030302f [...] After the fall-through, we similarly forced the var_off result into the wrong range [0x30303030,0x3030302f] suggesting later on that fixed bits must only be of 0x30303020 with 0x10000001f unknowns whereas such assumption can only be made when both bounds in hi32 range match. Originally, I was thinking to fix this by moving reg into a temp reg and use proper coerce_reg_to_size() helper on the temp reg where we can then based on that define the range tnum for later intersection: static void __reg_bound_offset32(struct bpf_reg_state *reg) { struct bpf_reg_state tmp = *reg; struct tnum lo32, hi32, range; coerce_reg_to_size(&tmp, 4); range = tnum_range(tmp.umin_value, tmp.umax_value); lo32 = tnum_cast(reg->var_off, 4); hi32 = tnum_lshift(tnum_rshift(reg->var_off, 32), 32); reg->var_off = tnum_or(hi32, tnum_intersect(lo32, range)); } In the case of the concrete example, this gives us a more conservative unknown section. Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000 and w1 <= 0x400 and w1 >= 0x200: max: 0b100000000000000000000000000000000000000 / 0x4000000000 var: 0b111111111111111111111111111111111111111 / 0x7fffffffff min: 0b010000000000000000000000000000000000000 / 0x2000000000 However, above new __reg_bound_offset32() has no effect on refining the knowledge of the register contents. Meaning, if the bounds in hi32 range mismatch we'll get the identity function given the range reg spans [0x0,0xffffffff] and we cast var_off into lo32 only to later on binary or it again with the hi32. Likewise, if the bounds in hi32 range match, then we mask both bounds with 0xffffffff, use the resulting umin/umax for the range to later intersect the lo32 with it. However, _prior_ called __reg_bound_offset() did already such intersection on the full reg and we therefore would only repeat the same operation on the lo32 part twice. Given this has no effect and the original commit had false assumptions, this patch reverts the code entirely which is also more straight forward for stable trees: apparently 581738a681b6 got auto-selected by Sasha's ML system and misclassified as a fix, so it got sucked into v5.4 where it should never have landed. A revert is low-risk also from a user PoV since it requires a recent kernel and llc to opt-into -mcpu=v3 BPF CPU to generate jmp32 instructions. A proper bounds refinement would need a significantly more complex approach which is currently being worked, but no stable material [0]. Hence revert is best option for stable. After the revert, the original reported program gets rejected as follows: 1: (7f) r0 >>= r0 2: (14) w0 -= 808464432 3: (07) r0 += 808464432 4: (b7) r1 = 808464432 5: (de) if w1 s<= w0 goto pc+0 R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x0; 0x1ffffffff)) R1_w=invP808464432 R10=fp0 6: (07) r0 += -2144337872 7: (14) w0 -= -1607454672 8: (25) if r0 > 0x30303030 goto pc+0 R0_w=invP(id=0,umax_value=808464432,var_off=(0x0; 0x3fffffff)) R1_w=invP808464432 R10=fp0 9: (76) if w0 s>= 0x303030 goto pc+2 R0=invP(id=0,umax_value=3158063,var_off=(0x0; 0x3fffff)) R1=invP808464432 R10=fp0 10: (30) r0 = *(u8 *)skb[808464432] BPF_LD_[ABS|IND] uses reserved fields processed 11 insns (limit 1000000) [...] [0] https://lore.kernel.org/bpf/158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower/T/ Fixes: 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions") Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330160324.15259-2-daniel@iogearbox.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f2d67fec0b43edce8c416101cdc52e71145b5fef upstream.

Anatoly has been fuzzing with kBdysch harness and reported a hang in
one of the outcomes:

  0: (b7) r0 = 808464432
  1: (7f) r0 >>= r0
  2: (14) w0 -= 808464432
  3: (07) r0 += 808464432
  4: (b7) r1 = 808464432
  5: (de) if w1 s<= w0 goto pc+0
   R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020;0x10000001f)) R1_w=invP808464432 R10=fp0
  6: (07) r0 += -2144337872
  7: (14) w0 -= -1607454672
  8: (25) if r0 > 0x30303030 goto pc+0
   R0_w=invP(id=0,umin_value=271581184,umax_value=271581311,var_off=(0x10300000;0x7f)) R1_w=invP808464432 R10=fp0
  9: (76) if w0 s>= 0x303030 goto pc+2
  12: (95) exit

  from 8 to 9: safe

  from 5 to 6: R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020;0x10000001f)) R1_w=invP808464432 R10=fp0
  6: (07) r0 += -2144337872
  7: (14) w0 -= -1607454672
  8: (25) if r0 > 0x30303030 goto pc+0
   R0_w=invP(id=0,umin_value=271581184,umax_value=271581311,var_off=(0x10300000;0x7f)) R1_w=invP808464432 R10=fp0
  9: safe

  from 8 to 9: safe
  verification time 589 usec
  stack depth 0
  processed 17 insns (limit 1000000) [...]

The underlying program was xlated as follows:

  # bpftool p d x i 9
   0: (b7) r0 = 808464432
   1: (7f) r0 >>= r0
   2: (14) w0 -= 808464432
   3: (07) r0 += 808464432
   4: (b7) r1 = 808464432
   5: (de) if w1 s<= w0 goto pc+0
   6: (07) r0 += -2144337872
   7: (14) w0 -= -1607454672
   8: (25) if r0 > 0x30303030 goto pc+0
   9: (76) if w0 s>= 0x303030 goto pc+2
  10: (05) goto pc-1
  11: (05) goto pc-1
  12: (95) exit

The verifier rewrote original instructions it recognized as dead code with
'goto pc-1', but reality differs from verifier simulation in that we're
actually able to trigger a hang due to hitting the 'goto pc-1' instructions.

Taking different examples to make the issue more obvious: in this example
we're probing bounds on a completely unknown scalar variable in r1:

  [...]
  5: R0_w=inv1 R1_w=inv(id=0) R10=fp0
  5: (18) r2 = 0x4000000000
  7: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R10=fp0
  7: (18) r3 = 0x2000000000
  9: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R10=fp0
  9: (18) r4 = 0x400
  11: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R10=fp0
  11: (18) r5 = 0x200
  13: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0
  13: (2d) if r1 > r2 goto pc+4
   R0_w=inv1 R1_w=inv(id=0,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0
  14: R0_w=inv1 R1_w=inv(id=0,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0
  14: (ad) if r1 < r3 goto pc+3
   R0_w=inv1 R1_w=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0
  15: R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0
  15: (2e) if w1 > w4 goto pc+2
   R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0
  16: R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0
  16: (ae) if w1 < w5 goto pc+1
   R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0
  [...]

We're first probing lower/upper bounds via jmp64, later we do a similar
check via jmp32 and examine the resulting var_off there. After fall-through
in insn 14, we get the following bounded r1 with 0x7fffffffff unknown marked
bits in the variable section.

Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000:

  max: 0b100000000000000000000000000000000000000 / 0x4000000000
  var: 0b111111111111111111111111111111111111111 / 0x7fffffffff
  min: 0b010000000000000000000000000000000000000 / 0x2000000000

Now, in insn 15 and 16, we perform a similar probe with lower/upper bounds
in jmp32.

Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000 and
                    w1 <= 0x400        and w1 >= 0x200:

  max: 0b100000000000000000000000000000000000000 / 0x4000000000
  var: 0b111111100000000000000000000000000000000 / 0x7f00000000
  min: 0b010000000000000000000000000000000000000 / 0x2000000000

The lower/upper bounds haven't changed since they have high bits set in
u64 space and the jmp32 tests can only refine bounds in the low bits.

However, for the var part the expectation would have been 0x7f000007ff
or something less precise up to 0x7fffffffff. A outcome of 0x7f00000000
is not correct since it would contradict the earlier probed bounds
where we know that the result should have been in [0x200,0x400] in u32
space. Therefore, tests with such info will lead to wrong verifier
assumptions later on like falsely predicting conditional jumps to be
always taken, etc.

The issue here is that __reg_bound_offset32()'s implementation from
commit 581738a681b6 ("bpf: Provide better register bounds after jmp32
instructions") makes an incorrect range assumption:

  static void __reg_bound_offset32(struct bpf_reg_state *reg)
  {
        u64 mask = 0xffffFFFF;
        struct tnum range = tnum_range(reg->umin_value & mask,
                                       reg->umax_value & mask);
        struct tnum lo32 = tnum_cast(reg->var_off, 4);
        struct tnum hi32 = tnum_lshift(tnum_rshift(reg->var_off, 32), 32);

        reg->var_off = tnum_or(hi32, tnum_intersect(lo32, range));
  }

In the above walk-through example, __reg_bound_offset32() as-is chose
a range after masking with 0xffffffff of [0x0,0x0] since umin:0x2000000000
and umax:0x4000000000 and therefore the lo32 part was clamped to 0x0 as
well. However, in the umin:0x2000000000 and umax:0x4000000000 range above
we'd end up with an actual possible interval of [0x0,0xffffffff] for u32
space instead.

In case of the original reproducer, the situation looked as follows at
insn 5 for r0:

  [...]
  5: R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x0; 0x1ffffffff)) R1_w=invP808464432 R10=fp0
                               0x30303030           0x13030302f
  5: (de) if w1 s<= w0 goto pc+0
   R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020; 0x10000001f)) R1_w=invP808464432 R10=fp0
                             0x30303030           0x13030302f
  [...]

After the fall-through, we similarly forced the var_off result into
the wrong range [0x30303030,0x3030302f] suggesting later on that fixed
bits must only be of 0x30303020 with 0x10000001f unknowns whereas such
assumption can only be made when both bounds in hi32 range match.

Originally, I was thinking to fix this by moving reg into a temp reg and
use proper coerce_reg_to_size() helper on the temp reg where we can then
based on that define the range tnum for later intersection:

  static void __reg_bound_offset32(struct bpf_reg_state *reg)
  {
        struct bpf_reg_state tmp = *reg;
        struct tnum lo32, hi32, range;

        coerce_reg_to_size(&tmp, 4);
        range = tnum_range(tmp.umin_value, tmp.umax_value);
        lo32 = tnum_cast(reg->var_off, 4);
        hi32 = tnum_lshift(tnum_rshift(reg->var_off, 32), 32);
        reg->var_off = tnum_or(hi32, tnum_intersect(lo32, range));
  }

In the case of the concrete example, this gives us a more conservative unknown
section. Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000 and
                             w1 <= 0x400        and w1 >= 0x200:

  max: 0b100000000000000000000000000000000000000 / 0x4000000000
  var: 0b111111111111111111111111111111111111111 / 0x7fffffffff
  min: 0b010000000000000000000000000000000000000 / 0x2000000000

However, above new __reg_bound_offset32() has no effect on refining the
knowledge of the register contents. Meaning, if the bounds in hi32 range
mismatch we'll get the identity function given the range reg spans
[0x0,0xffffffff] and we cast var_off into lo32 only to later on binary
or it again with the hi32.

Likewise, if the bounds in hi32 range match, then we mask both bounds
with 0xffffffff, use the resulting umin/umax for the range to later
intersect the lo32 with it. However, _prior_ called __reg_bound_offset()
did already such intersection on the full reg and we therefore would only
repeat the same operation on the lo32 part twice.

Given this has no effect and the original commit had false assumptions,
this patch reverts the code entirely which is also more straight forward
for stable trees: apparently 581738a681b6 got auto-selected by Sasha's
ML system and misclassified as a fix, so it got sucked into v5.4 where
it should never have landed. A revert is low-risk also from a user PoV
since it requires a recent kernel and llc to opt-into -mcpu=v3 BPF CPU
to generate jmp32 instructions. A proper bounds refinement would need a
significantly more complex approach which is currently being worked, but
no stable material [0]. Hence revert is best option for stable. After the
revert, the original reported program gets rejected as follows:

  1: (7f) r0 >>= r0
  2: (14) w0 -= 808464432
  3: (07) r0 += 808464432
  4: (b7) r1 = 808464432
  5: (de) if w1 s<= w0 goto pc+0
   R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x0; 0x1ffffffff)) R1_w=invP808464432 R10=fp0
  6: (07) r0 += -2144337872
  7: (14) w0 -= -1607454672
  8: (25) if r0 > 0x30303030 goto pc+0
   R0_w=invP(id=0,umax_value=808464432,var_off=(0x0; 0x3fffffff)) R1_w=invP808464432 R10=fp0
  9: (76) if w0 s>= 0x303030 goto pc+2
   R0=invP(id=0,umax_value=3158063,var_off=(0x0; 0x3fffff)) R1=invP808464432 R10=fp0
  10: (30) r0 = *(u8 *)skb[808464432]
  BPF_LD_[ABS|IND] uses reserved fields
  processed 11 insns (limit 1000000) [...]

  [0] https://lore.kernel.org/bpf/158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower/T/

Fixes: 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions")
Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200330160324.15259-2-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-01-23T07:10:16+00:00 David S. Miller davem@davemloft.net 2020-01-23T07:10:16+00:00 954b3c4397792c8614aa4aaf25030ae87ece8307 Alexei Starovoitov says: ==================== pull-request: bpf-next 2020-01-22 The following pull-request contains BPF updates for your *net-next* tree. We've added 92 non-merge commits during the last 16 day(s) which contain a total of 320 files changed, 7532 insertions(+), 1448 deletions(-). The main changes are: 1) function by function verification and program extensions from Alexei. 2) massive cleanup of selftests/bpf from Toke and Andrii. 3) batched bpf map operations from Brian and Yonghong. 4) tcp congestion control in bpf from Martin. 5) bulking for non-map xdp_redirect form Toke. 6) bpf_send_signal_thread helper from Yonghong. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> 
Alexei Starovoitov says:

====================
pull-request: bpf-next 2020-01-22

The following pull-request contains BPF updates for your *net-next* tree.

We've added 92 non-merge commits during the last 16 day(s) which contain
a total of 320 files changed, 7532 insertions(+), 1448 deletions(-).

The main changes are:

1) function by function verification and program extensions from Alexei.

2) massive cleanup of selftests/bpf from Toke and Andrii.

3) batched bpf map operations from Brian and Yonghong.

4) tcp congestion control in bpf from Martin.

5) bulking for non-map xdp_redirect form Toke.

6) bpf_send_signal_thread helper from Yonghong.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
bpf: Add BPF_FUNC_jiffies64 2020-01-23T00:30:10+00:00 Martin KaFai Lau kafai@fb.com 2020-01-22T23:36:46+00:00 5576b991e9c1a11d2cc21c4b94fc75ec27603896 This patch adds a helper to read the 64bit jiffies. It will be used in a later patch to implement the bpf_cubic.c. The helper is inlined for jit_requested and 64 BITS_PER_LONG as the map_gen_lookup(). Other cases could be considered together with map_gen_lookup() if needed. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200122233646.903260-1-kafai@fb.com 
This patch adds a helper to read the 64bit jiffies.  It will be used
in a later patch to implement the bpf_cubic.c.

The helper is inlined for jit_requested and 64 BITS_PER_LONG
as the map_gen_lookup().  Other cases could be considered together
with map_gen_lookup() if needed.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200122233646.903260-1-kafai@fb.com