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media: v4l2-h264: Fix memcmp() size in B1 reference list comparison

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In v4l2_h264_build_b_ref_lists(), the B0/B1 list equality
check passes the entry count builder->num_valid to memcmp()
instead of a byte size. Since struct v4l2_h264_reference is
two bytes (fields and index), only half of each list is
compared, so distinct lists can be wrongly treated as equal
and trigger an incorrect swap(b1_reflist[0], b1_reflist[1]).

Change the memcmp() size argument to sizeof(b1_reflist[0]) *
builder->num_valid so that the full byte length of both
reference lists is compared.

Fixes: 624922a273 ("media: v4l2-core: Add helpers to build the H264 P/B0/B1 reflists")
Suggested-by: Nicolas Dufresne <nicolas@ndufresne.ca>
Cc: stable@vger.kernel.org
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Haotian Zhang 2026-09-01 10:23:09 +08:00 committed by Hans Verkuil
parent e04ffff543
commit 10e59fbdef
1 changed files with 2 additions and 1 deletions
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3
drivers/media/v4l2-core/v4l2-h264.c
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@ -440,7 +440,8 @@ v4l2_h264_build_b_ref_lists(const struct v4l2_h264_reflist_builder *builder,
}
if (builder->num_valid > 1 &&
!memcmp(b1_reflist, b0_reflist, builder->num_valid))
!memcmp(b1_reflist, b0_reflist,
sizeof(b1_reflist[0]) * builder->num_valid))
swap(b1_reflist[0], b1_reflist[1]);
print_ref_list_b(builder, b0_reflist, 0);