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| author | Andrii Nakryiko <[email protected]> | 2023-12-05 10:42:41 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <[email protected]> | 2024-01-25 15:35:22 -0800 |
| commit | 8dc15b0670594543c356567a1a45b0182ec63174 (patch) | |
| tree | 38f8254f4c5f60f36f7c3e1ba2b27c2cdfde2214 | |
| parent | 25a17a269b446296a5e1f116fd5712557e776880 (diff) | |
| download | linux-8dc15b0670594543c356567a1a45b0182ec63174.tar.gz | |
bpf: fix check for attempt to corrupt spilled pointer
[ Upstream commit ab125ed3ec1c10ccc36bc98c7a4256ad114a3dae ]
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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
| -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 2deae0db03e8d8..24152ac6a393cc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4330,7 +4330,7 @@ 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; |