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bpf: Check tail zero of bpf_common_attr using offsetofend

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Because of the 8-byte alignment, the compiler will pad struct
bpf_common_attr to 24 bytes. That said, sizeof(attr_common) is 24 instead
of 20.

When check tail zero using sizeof(attr_common) in
bpf_check_uarg_tail_zero(), there will be 4 bytes that won't be checked.

To also check the padding 4 bytes, replace sizeof(attr_common) with
offsetofend(struct bpf_common_attr, log_true_size).

Fixes: f28771c069 ("bpf: Extend BPF syscall with common attributes support")
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260518145446.6794-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Leon Hwang 2026-05-18 22:54:42 +08:00 committed by Alexei Starovoitov
parent 576482b55c
commit f05ddc6771
1 changed files with 3 additions and 1 deletions
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4
kernel/bpf/syscall.c
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@ -6278,7 +6278,9 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size,
memset(&attr_common, 0, sizeof(attr_common));
if (cmd & BPF_COMMON_ATTRS) {
err = bpf_check_uarg_tail_zero(uattr_common, sizeof(attr_common), size_common);
err = bpf_check_uarg_tail_zero(uattr_common,
offsetofend(struct bpf_common_attr, log_true_size),
size_common);
if (err)
return err;