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avcodec/h264: Fix race between slices where one overwrites data from the next 

Fixes non deterministic crash in ticket4408/fuzz2.264
Likely fixes other samples as well

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 43b434210e)

Conflicts:

	libavcodec/h264.h
	libavcodec/h264_slice.c
(cherry picked from commit dbbc42858e87cdd04e6c3b7694f8b394d4bfcdc6)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2015-04-07 00:40:21 +02:00
parent 8968de6c61
commit 48f616ceee
2 changed files with 39 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
libavcodec/h264.h
View File

@ -539,6 +539,7 @@ typedef struct H264Context {
int mb_x, mb_y;
int resync_mb_x;
int resync_mb_y;
int mb_index_end;
int mb_skip_run;
int mb_height, mb_width;
int mb_stride;

43
libavcodec/h264_slice.c
View File

@ -2445,8 +2445,17 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
for (;;) {
// START_TIMER
int ret = ff_h264_decode_mb_cabac(h);
int eos;
int ret, eos;
if (h->mb_x + h->mb_y * h->mb_width >= h->mb_index_end) {
av_log(h->avctx, AV_LOG_ERROR, "Slice overlaps next at %d\n",
h->mb_index_end);
er_add_slice(h, h->resync_mb_x, h->resync_mb_y, h->mb_x,
h->mb_y, ER_MB_ERROR);
return AVERROR_INVALIDDATA;
}
ret = ff_h264_decode_mb_cabac(h);
// STOP_TIMER("decode_mb_cabac")
if (ret >= 0)
@ -2508,7 +2517,17 @@ static int decode_slice(struct AVCodecContext *avctx, void *arg)
}
} else {
for (;;) {
int ret = ff_h264_decode_mb_cavlc(h);
int ret;
if (h->mb_x + h->mb_y * h->mb_width >= h->mb_index_end) {
av_log(h->avctx, AV_LOG_ERROR, "Slice overlaps next at %d\n",
h->mb_index_end);
er_add_slice(h, h->resync_mb_x, h->resync_mb_y, h->mb_x,
h->mb_y, ER_MB_ERROR);
return AVERROR_INVALIDDATA;
}
ret = ff_h264_decode_mb_cavlc(h);
if (ret >= 0)
ff_h264_hl_decode_mb(h);
@ -2596,19 +2615,33 @@ int ff_h264_execute_decode_slices(H264Context *h, unsigned context_count)
av_assert0(h->mb_y < h->mb_height);
h->mb_index_end = INT_MAX;
if (h->avctx->hwaccel ||
h->avctx->codec->capabilities & CODEC_CAP_HWACCEL_VDPAU)
return 0;
if (context_count == 1) {
return decode_slice(avctx, &h);
} else {
int j, mb_index;
av_assert0(context_count > 0);
for (i = 1; i < context_count; i++) {
for (i = 0; i < context_count; i++) {
int mb_index_end = h->mb_width * h->mb_height;
hx = h->thread_context[i];
if (CONFIG_ERROR_RESILIENCE) {
mb_index = hx->resync_mb_x + hx->resync_mb_y * h->mb_width;
if (CONFIG_ERROR_RESILIENCE && i) {
hx->er.error_count = 0;
}
hx->x264_build = h->x264_build;
for (j = 0; j < context_count; j++) {
H264Context *sl2 = h->thread_context[j];
int mb_index2 = sl2->resync_mb_x + sl2->resync_mb_y * h->mb_width;
if (i==j || mb_index > mb_index2)
continue;
mb_index_end = FFMIN(mb_index_end, mb_index2);
}
hx->mb_index_end = mb_index_end;
}
avctx->execute(avctx, decode_slice, h->thread_context,