[FFmpeg-devel] [PATCH 3/3] h264: fix data-race with FF_DECODE_ERROR_DECODE_SLICES - Thomas Guillem via ffmpeg-devel

From: Thomas Guillem via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>
To: ffmpeg-devel@ffmpeg.org
Cc: Thomas Guillem <thomas@gllm.fr>
Subject: [FFmpeg-devel] [PATCH 3/3] h264: fix data-race with FF_DECODE_ERROR_DECODE_SLICES
Date: Tue, 12 Sep 2023 13:40:15 +0200
Message-ID: <20230912114015.59937-3-thomas@gllm.fr> (raw)
In-Reply-To: <20230912114015.59937-1-thomas@gllm.fr>

Same than the previous commit but with FF_DECODE_ERROR_DECODE_SLICES

Fix the following data-race:

WARNING: ThreadSanitizer: data race (pid=55935)
  Write of size 4 at 0x7b5000009378 by thread T1 (mutexes: write M608):
    #0 decode_nal_units src/libavcodec/h264dec.c:742 (ffmpeg+0xb19dd6)
    #1 h264_decode_frame src/libavcodec/h264dec.c:1016 (ffmpeg+0xb19dd6)
    #2 frame_worker_thread src/libavcodec/pthread_frame.c:228 (ffmpeg+0xdeea7e)

  Previous read of size 4 at 0x7b5000009378 by thread T14 (mutexes: write M610):
    #0 frame_copy_props src/libavutil/frame.c:321 (ffmpeg+0x1793759)
    #1 av_frame_replace src/libavutil/frame.c:530 (ffmpeg+0x1794714)
    #2 ff_thread_replace_frame src/libavcodec/utils.c:898 (ffmpeg+0xfb1d0f)
    #3 ff_h264_replace_picture src/libavcodec/h264_picture.c:159 (ffmpeg+0x149cd3d)
    #4 ff_h264_update_thread_context src/libavcodec/h264_slice.c:413 (ffmpeg+0x14abf04)
    #5 update_context_from_thread src/libavcodec/pthread_frame.c:355 (ffmpeg+0xdec39c)
    #6 submit_packet src/libavcodec/pthread_frame.c:494 (ffmpeg+0xdecee3)
    #7 ff_thread_decode_frame src/libavcodec/pthread_frame.c:545 (ffmpeg+0xdecee3)
    #8 decode_simple_internal src/libavcodec/decode.c:431 (ffmpeg+0x9e1e20)
    #9 decode_simple_receive_frame src/libavcodec/decode.c:607 (ffmpeg+0x9e1e20)
    #10 decode_receive_frame_internal src/libavcodec/decode.c:635 (ffmpeg+0x9e1e20)
    #11 avcodec_send_packet src/libavcodec/decode.c:732 (ffmpeg+0x9e28fa)
    #12 packet_decode src/fftools/ffmpeg_dec.c:555 (ffmpeg+0x229888)
    #13 decoder_thread src/fftools/ffmpeg_dec.c:702 (ffmpeg+0x229888)
---
 libavcodec/h264dec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c
index 24e849fc5b..b82ca8f14f 100644
--- a/libavcodec/h264dec.c
+++ b/libavcodec/h264dec.c
@@ -739,7 +739,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
 
     // set decode_error_flags to allow users to detect concealed decoding errors
     if ((ret < 0 || h->er.error_occurred) && h->cur_pic_ptr) {
-        h->cur_pic_ptr->f->decode_error_flags |= FF_DECODE_ERROR_DECODE_SLICES;
+        h->cur_pic_ptr->decode_error_flags |= FF_DECODE_ERROR_DECODE_SLICES;
     }
 
     ret = 0;
-- 
2.39.2

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