[FFmpeg-devel] [PATCH v2] avcodec/decode: guard against NULL hw_frames_ctx
Dmitry Rogozhkin
dmitry.v.rogozhkin at intel.com
Tue Nov 14 21:14:32 EET 2023
Guard against segfault running VLC decoding under msys2 [1]:
Thread 33 received signal SIGSEGV, Segmentation fault.
[Switching to Thread 37728.0xadd0]
ff_hwaccel_frame_priv_alloc (avctx=0x6447b00, hwaccel_picture_private=0x65dfd00)
at libavcodec/decode.c:1848
1848 frames_ctx = (AVHWFramesContext *)avctx->hw_frames_ctx->data;
(gdb) bt
at libavcodec/decode.c:1848
at libavcodec/h264_slice.c:208
first_slice=1) at libavcodec/h264_slice.c:1599
at libavcodec/h264_slice.c:2130
at libavcodec/h264dec.c:652
got_frame=0x646e4b0, avpkt=0x64522c0) at libavcodec/h264dec.c:1048
(gdb) p avctx
$1 = (AVCodecContext *) 0x6447b00
(gdb) p avctx->hw_frames_ctx
$2 = (AVBufferRef *) 0x0
v2: check for free_frame_priv (Hendrik)
See[1]: https://github.com/msys2/MINGW-packages/pull/19050
Fixes: be07145109 ("avcodec: add AVHWAccel.free_frame_priv callback")
CC: Lynne <dev at lynne.ee>
CC: Christoph Reiter <reiter.christoph at gmail.com>
Signed-off-by: Dmitry Rogozhkin <dmitry.v.rogozhkin at intel.com>
---
libavcodec/decode.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/libavcodec/decode.c b/libavcodec/decode.c
index ad39021..58f887d 100644
--- a/libavcodec/decode.c
+++ b/libavcodec/decode.c
@@ -1838,17 +1838,29 @@ int ff_copy_palette(void *dst, const AVPacket *src, void *logctx)
int ff_hwaccel_frame_priv_alloc(AVCodecContext *avctx, void **hwaccel_picture_private)
{
const FFHWAccel *hwaccel = ffhwaccel(avctx->hwaccel);
- AVHWFramesContext *frames_ctx;
if (!hwaccel || !hwaccel->frame_priv_data_size)
return 0;
av_assert0(!*hwaccel_picture_private);
- frames_ctx = (AVHWFramesContext *)avctx->hw_frames_ctx->data;
- *hwaccel_picture_private = ff_refstruct_alloc_ext(hwaccel->frame_priv_data_size, 0,
- frames_ctx->device_ctx,
- hwaccel->free_frame_priv);
+ if (hwaccel->free_frame_priv) {
+ AVHWFramesContext *frames_ctx;
+
+ if (!avctx->hw_frames_ctx)
+ return AVERROR(ENOMEM);
+
+ frames_ctx = (AVHWFramesContext *) avctx->hw_frames_ctx->data;
+ if (!frames_ctx)
+ return AVERROR(ENOMEM);
+
+ *hwaccel_picture_private = ff_refstruct_alloc_ext(hwaccel->frame_priv_data_size, 0,
+ frames_ctx->device_ctx,
+ hwaccel->free_frame_priv);
+ } else {
+ *hwaccel_picture_private = ff_refstruct_allocz(hwaccel->frame_priv_data_size);
+ }
+
if (!*hwaccel_picture_private)
return AVERROR(ENOMEM);
--
1.8.3.1
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