linux.git/kernel/bpf/verifier.c, branch v7.1-rc5 Linux kernel source tree bpf: Check global subprog exception paths 2026-05-17T18:15:05+00:00 Kumar Kartikeya Dwivedi memxor@gmail.com 2026-05-17T07:55:28+00:00 3d562d35a044ae798cab421c65a116f8cedfa5d4 Global subprogs are verified independently and are not descended into when their callers are symbolically executed. This means a caller can hold references or locks across a global subprog call that may throw, while the verifier only checks the non-exceptional return path at the call site. Record whether a subprog might throw in the CFG summary pass, alongside the existing might_sleep and packet-data-changing summaries, and propagate that effect through reachable callees. When a global subprog is marked as possibly throwing, push the normal continuation and validate the exceptional path immediately at the call site, avoiding a synthetic exception state and associated special case in the pruning checks. Fixes: f18b03fabaa9 ("bpf: Implement BPF exceptions") Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20260517075530.3461166-2-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Global subprogs are verified independently and are not descended into
when their callers are symbolically executed. This means a caller can
hold references or locks across a global subprog call that may throw,
while the verifier only checks the non-exceptional return path at the
call site.

Record whether a subprog might throw in the CFG summary pass, alongside
the existing might_sleep and packet-data-changing summaries, and
propagate that effect through reachable callees.

When a global subprog is marked as possibly throwing, push the normal
continuation and validate the exceptional path immediately at the call
site, avoiding a synthetic exception state and associated special case
in the pruning checks.

Fixes: f18b03fabaa9 ("bpf: Implement BPF exceptions")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260517075530.3461166-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: make bpf_session_is_return() reference optional 2026-05-15T16:49:16+00:00 Arnd Bergmann arnd@arndb.de 2026-05-15T11:32:32+00:00 a828abbb897657451d96ad7bf20f1893ac983bb9 Building without CONFIG_BPF_EVENTS produces a build-time warning: WARN: resolve_btfids: unresolved symbol bpf_session_is_return The function is actually defined in kernel/trace/bpf_trace.o, which is built conditionally based on configuration. Make the reference to this function conditional as well, as is already done in the bpf verifier for other functions. Fixes: 8fe4dc4f6456 ("bpf: change prototype of bpf_session_{cookie,is_return}") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20260515113242.2706303-1-arnd@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Building without CONFIG_BPF_EVENTS produces a build-time
warning:

WARN: resolve_btfids: unresolved symbol bpf_session_is_return

The function is actually defined in kernel/trace/bpf_trace.o,
which is built conditionally based on configuration.

Make the reference to this function conditional as well,
as is already done in the bpf verifier for other functions.

Fixes: 8fe4dc4f6456 ("bpf: change prototype of bpf_session_{cookie,is_return}")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20260515113242.2706303-1-arnd@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Fix NULL deref in map_kptr_match_type for scalar regs 2026-04-16T22:20:26+00:00 Mykyta Yatsenko yatsenko@meta.com 2026-04-16T18:08:07+00:00 4d0a375887ab4d49e4da1ff10f9606cab8f7c3ad Commit ab6c637ad027 ("bpf: Fix a bpf_kptr_xchg() issue with local kptr") refactored map_kptr_match_type() to branch on btf_is_kernel() before checking base_type(). A scalar register stored into a kptr slot has no btf, so the btf_is_kernel(reg->btf) call dereferences NULL. Move the base_type() != PTR_TO_BTF_ID guard before any reg->btf access. Fixes: ab6c637ad027 ("bpf: Fix a bpf_kptr_xchg() issue with local kptr") Reported-by: Hiker Cl <clhiker365@gmail.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221372 Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Acked-by: Paul Chaignon <paul.chaignon@gmail.com> Link: https://lore.kernel.org/r/20260416-kptr_crash-v1-1-5589356584b4@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Commit ab6c637ad027 ("bpf: Fix a bpf_kptr_xchg() issue with local
kptr") refactored map_kptr_match_type() to branch on btf_is_kernel()
before checking base_type(). A scalar register stored into a kptr
slot has no btf, so the btf_is_kernel(reg->btf) call dereferences
NULL.

Move the base_type() != PTR_TO_BTF_ID guard before any reg->btf
access.

Fixes: ab6c637ad027 ("bpf: Fix a bpf_kptr_xchg() issue with local kptr")
Reported-by: Hiker Cl <clhiker365@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221372
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/20260416-kptr_crash-v1-1-5589356584b4@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Add helper to detect indirect jump targets 2026-04-16T14:03:40+00:00 Xu Kuohai xukuohai@huawei.com 2026-04-16T06:43:39+00:00 07ae6c130b46cf5e3e1a7dc5c1889fefe9adc2d3 Introduce helper bpf_insn_is_indirect_target to check whether a BPF instruction is an indirect jump target. Since the verifier knows which instructions are indirect jump targets, add a new flag indirect_target to struct bpf_insn_aux_data to mark them. The verifier sets this flag when verifying an indirect jump target instruction, and the helper checks the flag to determine whether an instruction is an indirect jump target. Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com> #v8 Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> #v12 Signed-off-by: Xu Kuohai <xukuohai@huawei.com> Link: https://lore.kernel.org/r/20260416064341.151802-4-xukuohai@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Introduce helper bpf_insn_is_indirect_target to check whether a BPF
instruction is an indirect jump target.

Since the verifier knows which instructions are indirect jump targets,
add a new flag indirect_target to struct bpf_insn_aux_data to mark
them. The verifier sets this flag when verifying an indirect jump target
instruction, and the helper checks the flag to determine whether an
instruction is an indirect jump target.

Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com> #v8
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> #v12
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20260416064341.151802-4-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Pass bpf_verifier_env to JIT 2026-04-16T14:03:40+00:00 Xu Kuohai xukuohai@huawei.com 2026-04-16T06:43:38+00:00 d9ef13f72711f2dad64cd4445472ded98fb6c954 Pass bpf_verifier_env to bpf_int_jit_compile(). The follow-up patch will use env->insn_aux_data in the JIT stage to detect indirect jump targets. Since bpf_prog_select_runtime() can be called by cbpf and lib/test_bpf.c code without verifier, introduce helper __bpf_prog_select_runtime() to accept the env parameter. Remove the call to bpf_prog_select_runtime() in bpf_prog_load(), and switch to call __bpf_prog_select_runtime() in the verifier, with env variable passed. The original bpf_prog_select_runtime() is preserved for cbpf and lib/test_bpf.c, where env is NULL. Now all constants blinding calls are moved into the verifier, except the cbpf and lib/test_bpf.c cases. The instructions arrays are adjusted by bpf_patch_insn_data() function for normal cases, so there is no need to call adjust_insn_arrays() in bpf_jit_blind_constants(). Remove it. Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com> # v8 Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> # v12 Acked-by: Hengqi Chen <hengqi.chen@gmail.com> # v14 Signed-off-by: Xu Kuohai <xukuohai@huawei.com> Link: https://lore.kernel.org/r/20260416064341.151802-3-xukuohai@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Pass bpf_verifier_env to bpf_int_jit_compile(). The follow-up patch will
use env->insn_aux_data in the JIT stage to detect indirect jump targets.

Since bpf_prog_select_runtime() can be called by cbpf and lib/test_bpf.c
code without verifier, introduce helper __bpf_prog_select_runtime()
to accept the env parameter.

Remove the call to bpf_prog_select_runtime() in bpf_prog_load(), and
switch to call __bpf_prog_select_runtime() in the verifier, with env
variable passed. The original bpf_prog_select_runtime() is preserved for
cbpf and lib/test_bpf.c, where env is NULL.

Now all constants blinding calls are moved into the verifier, except
the cbpf and lib/test_bpf.c cases. The instructions arrays are adjusted
by bpf_patch_insn_data() function for normal cases, so there is no need
to call adjust_insn_arrays() in bpf_jit_blind_constants(). Remove it.

Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com> # v8
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> # v12
Acked-by: Hengqi Chen <hengqi.chen@gmail.com> # v14
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20260416064341.151802-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Allow instructions with arena source and non-arena dest registers 2026-04-12T19:47:39+00:00 Emil Tsalapatis emil@etsalapatis.com 2026-04-12T17:45:38+00:00 ac61bffe91d4bda08806e12957c6d64756d042db The compiler sometimes stores the result of a PTR_TO_ARENA and SCALAR operation into the scalar register rather than the pointer register. Relax the verifier to allow operations between a source arena register and a destination non-arena register, marking the destination's value as a PTR_TO_ARENA. Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com> Acked-by: Song Liu <song@kernel.org> Fixes: 6082b6c328b5 ("bpf: Recognize addr_space_cast instruction in the verifier.") Link: https://lore.kernel.org/r/20260412174546.18684-2-emil@etsalapatis.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
The compiler sometimes stores the result of a PTR_TO_ARENA and SCALAR
operation into the scalar register rather than the pointer register.
Relax the verifier to allow operations between a source arena register
and a destination non-arena register, marking the destination's value
as a PTR_TO_ARENA.

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Acked-by: Song Liu <song@kernel.org>
Fixes: 6082b6c328b5 ("bpf: Recognize addr_space_cast instruction in the verifier.")
Link: https://lore.kernel.org/r/20260412174546.18684-2-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: add missing fsession to the verifier log 2026-04-12T19:42:38+00:00 Menglong Dong menglong8.dong@gmail.com 2026-04-12T06:03:44+00:00 9fd19e3ed7751bbd28cfca1e3f73811e2f1a370f The fsession attach type is missed in the verifier log in check_get_func_ip(), bpf_check_attach_target() and check_attach_btf_id(). Update them to make the verifier log proper. Meanwhile, update the corresponding selftests. Acked-by: Leon Hwang <leon.hwang@linux.dev> Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn> Link: https://lore.kernel.org/r/20260412060346.142007-2-dongml2@chinatelecom.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
The fsession attach type is missed in the verifier log in
check_get_func_ip(), bpf_check_attach_target() and check_attach_btf_id().
Update them to make the verifier log proper. Meanwhile, update the
corresponding selftests.

Acked-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20260412060346.142007-2-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Move BTF checking logic into check_btf.c 2026-04-12T19:37:04+00:00 Alexei Starovoitov ast@kernel.org 2026-04-12T15:29:35+00:00 99a832a2b5b8a8ecc1a2bdd64017892caf4aa096 BTF validation logic is independent from the main verifier. Move it into check_btf.c Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20260412152936.54262-7-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
BTF validation logic is independent from the main verifier.
Move it into check_btf.c

Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260412152936.54262-7-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Move backtracking logic to backtrack.c 2026-04-12T19:36:58+00:00 Alexei Starovoitov ast@kernel.org 2026-04-12T15:29:34+00:00 ed0b9710bd2efbe663d89728cd9c680c31c6a4e3 Move precision propagation and backtracking logic to backtrack.c to reduce verifier.c size. No functional changes. Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20260412152936.54262-6-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Move precision propagation and backtracking logic to backtrack.c
to reduce verifier.c size.

No functional changes.

Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260412152936.54262-6-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf: Move state equivalence logic to states.c 2026-04-12T19:36:52+00:00 Alexei Starovoitov ast@kernel.org 2026-04-12T15:29:33+00:00 c82834a5a11f743f2926107d8f8150e80742b814 verifier.c is huge. Move is_state_visited() to states.c, so that all state equivalence logic is in one file. Mechanical move. No functional changes. Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20260412152936.54262-5-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
verifier.c is huge. Move is_state_visited() to states.c,
so that all state equivalence logic is in one file.

Mechanical move. No functional changes.

Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260412152936.54262-5-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>