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Git pushed a commit to branch release/8.0
in repository ffmpeg.
The following commit(s) were added to refs/heads/release/8.0 by this push:
new 4ea01b43b6 avcodec/h264_direct: keep the colocated type interlaced in
the field branch
4ea01b43b6 is described below
commit 4ea01b43b6a9b3c6b47bb75abf5fc3f1208d709e
Author: Kacper Michajłow <[email protected]>
AuthorDate: Fri Oct 30 01:43:12 2026 +0100
Commit: ffmpeg-devel <[email protected]>
CommitDate: Wed Nov 4 05:30:09 2026 +0000
avcodec/h264_direct: keep the colocated type interlaced in the field branch
A colocated field picture always takes the field branch, but macroblocks
that were never decoded in a broken field picture keep a stale mb_type
without MB_TYPE_INTERLACED. The later IS_INTERLACED(mb_type_col[0])
check then picked the frame to frame path with the field remapping,
which reads the colocated motion vectors past the end of the picture.
Set the flag on the colocated type whenever the field branch is taken,
decoded macroblocks have it already.
Fixes: heap-buffer-overflow (read)
Fixes:
553213954/clusterfuzz-testcase-minimized-fuzzer_loadfile_mkv-6112026834042880
Found-by: https://github.com/google/oss-fuzz/tree/master/projects/mpv
Signed-off-by: Kacper Michajłow <[email protected]>
(cherry picked from commit 2546b6f061fe6bc869ac9a1c0ed892555bd24402)
---
libavcodec/h264_direct.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/libavcodec/h264_direct.c b/libavcodec/h264_direct.c
index 1bc4f911ba..44942f17a8 100644
--- a/libavcodec/h264_direct.c
+++ b/libavcodec/h264_direct.c
@@ -212,6 +212,7 @@ static void pred_spatial_direct_motion(const H264Context
*const h, H264SliceCont
int b4_stride = h->b_stride;
int mb_xy = sl->mb_xy, mb_y = sl->mb_y;
int mb_type_col[2];
+ int col_field = 0;
const int16_t (*l1mv0)[2], (*l1mv1)[2];
const int8_t *l1ref0, *l1ref1;
const int is_b8x8 = IS_8X8(*mb_type);
@@ -303,6 +304,9 @@ static void pred_spatial_direct_motion(const H264Context
*const h, H264SliceCont
mb_y += sl->col_fieldoff;
mb_xy += h->mb_stride * sl->col_fieldoff; // non-zero for FL -> FL
& differ parity
}
+ // Undecoded macroblocks of a broken field picture lack the flag, the
+ // colocated type has to agree with the branch taken here.
+ col_field = MB_TYPE_INTERLACED;
goto single_col;
} else { // AFL/AFR/FR/FL ->
AFR/FR
if (IS_INTERLACED(*mb_type)) { // AFL /FL ->
AFR/FR
@@ -329,7 +333,7 @@ static void pred_spatial_direct_motion(const H264Context
*const h, H264SliceCont
} else { // AFR/FR ->
AFR/FR
single_col:
mb_type_col[0] =
- mb_type_col[1] = sl->ref_list[1][0].parent->mb_type[mb_xy];
+ mb_type_col[1] = sl->ref_list[1][0].parent->mb_type[mb_xy] |
col_field;
sub_mb_type |= MB_TYPE_16x16 | MB_TYPE_DIRECT2; /* B_SUB_8x8 */
if (!is_b8x8 && (mb_type_col[0] & MB_TYPE_16x16_OR_INTRA)) {
@@ -500,6 +504,7 @@ static void pred_temp_direct_motion(const H264Context
*const h, H264SliceContext
int b4_stride = h->b_stride;
int mb_xy = sl->mb_xy, mb_y = sl->mb_y;
int mb_type_col[2];
+ int col_field = 0;
const int16_t (*l1mv0)[2], (*l1mv1)[2];
const int8_t *l1ref0, *l1ref1;
const int is_b8x8 = IS_8X8(*mb_type);
@@ -522,6 +527,9 @@ static void pred_temp_direct_motion(const H264Context
*const h, H264SliceContext
mb_y += sl->col_fieldoff;
mb_xy += h->mb_stride * sl->col_fieldoff; // non-zero for FL -> FL
& differ parity
}
+ // Undecoded macroblocks of a broken field picture lack the flag, the
+ // colocated type has to agree with the branch taken here.
+ col_field = MB_TYPE_INTERLACED;
goto single_col;
} else { // AFL/AFR/FR/FL -> AFR/FR
if (IS_INTERLACED(*mb_type)) { // AFL /FL -> AFR/FR
@@ -551,7 +559,7 @@ static void pred_temp_direct_motion(const H264Context
*const h, H264SliceContext
} else { // AFR/FR -> AFR/FR
single_col:
mb_type_col[0] =
- mb_type_col[1] = sl->ref_list[1][0].parent->mb_type[mb_xy];
+ mb_type_col[1] = sl->ref_list[1][0].parent->mb_type[mb_xy] |
col_field;
sub_mb_type = MB_TYPE_16x16 | MB_TYPE_P0L0 | MB_TYPE_P0L1 |
MB_TYPE_DIRECT2; /* B_SUB_8x8 */
--
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