[FFmpeg-devel] [PATCH] avutil/hwcontext_dxva2: No longer improperly freeing IDirect3DSurface9 objects
Aaron Levinson
alevinsn at aracnet.com
Tue May 16 14:09:28 EEST 2017
Purpose: No longer improperly freeing IDirect3DSurface9 objects in
hwcontext_dxva2.c. Added dxva2_pool_release_dummy() and using it in
call to av_buffer_create() in dxva2_pool_alloc(). Prior to this
change, av_buffer_create() was called with NULL for the third
argument, which indicates that av_buffer_default_free() should be used
to free the buffer's data. Eventually, it gets to buffer_pool_free()
and calls buf->free() on a surface object (which is
av_buffer_default_free()). This can result in a crash when the debug
version of the C-runtime is used on Windows. While it doesn't appear
to result in a crash when the release version of the C-runtime is used
on Windows, it likely results in memory corruption, since av_free() is
being called on memory that was allocated using
IDirectXVideoAccelerationService::CreateSurface().
Signed-off-by: Aaron Levinson <alevinsn at aracnet.com>
---
libavutil/hwcontext_dxva2.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/libavutil/hwcontext_dxva2.c b/libavutil/hwcontext_dxva2.c
index 4ed0d56..6c41788 100644
--- a/libavutil/hwcontext_dxva2.c
+++ b/libavutil/hwcontext_dxva2.c
@@ -121,6 +121,13 @@ static void dxva2_frames_uninit(AVHWFramesContext *ctx)
}
}
+static void dxva2_pool_release_dummy(void *opaque, uint8_t *data)
+{
+ // important not to free anything here--data is a surface object
+ // associated with the call to CreateSurface(), and these surfaces are
+ // released in dxva2_frames_uninit()
+}
+
static AVBufferRef *dxva2_pool_alloc(void *opaque, int size)
{
AVHWFramesContext *ctx = (AVHWFramesContext*)opaque;
@@ -130,7 +137,7 @@ static AVBufferRef *dxva2_pool_alloc(void *opaque, int size)
if (s->nb_surfaces_used < hwctx->nb_surfaces) {
s->nb_surfaces_used++;
return av_buffer_create((uint8_t*)s->surfaces_internal[s->nb_surfaces_used - 1],
- sizeof(*hwctx->surfaces), NULL, 0, 0);
+ sizeof(*hwctx->surfaces), dxva2_pool_release_dummy, 0, 0);
}
return NULL;
--
2.10.1.windows.1
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