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| author | Andrii Nakryiko <andrii@kernel.org> | 2023-12-05 10:42:41 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-12-05 13:40:20 -0800 |
| commit | ab125ed3ec1c10ccc36bc98c7a4256ad114a3dae (patch) | |
| tree | 0c4185c31afa6f73b9a5f0ef6b9f9c9621cc662c /kernel | |
| parent | selftests/bpf: add stack access precision test (diff) | |
| download | linux-ab125ed3ec1c10ccc36bc98c7a4256ad114a3dae.tar.gz linux-ab125ed3ec1c10ccc36bc98c7a4256ad114a3dae.zip | |
bpf: fix check for attempt to corrupt spilled pointer
When register is spilled onto a stack as a 1/2/4-byte register, we set
slot_type[BPF_REG_SIZE - 1] (plus potentially few more below it,
depending on actual spill size). So to check if some stack slot has
spilled register we need to consult slot_type[7], not slot_type[0].
To avoid the need to remember and double-check this in the future, just
use is_spilled_reg() helper.
Fixes: 27113c59b6d0 ("bpf: Check the other end of slot_type for STACK_SPILL")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9bc16dc66465..3edca06de9fd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4431,7 +4431,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, * so it's aligned access and [off, off + size) are within stack limits */ if (!env->allow_ptr_leaks && - state->stack[spi].slot_type[0] == STACK_SPILL && + is_spilled_reg(&state->stack[spi]) && size != BPF_REG_SIZE) { verbose(env, "attempt to corrupt spilled pointer on stack\n"); return -EACCES; |