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From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
To: ffmpeg-devel@ffmpeg.org
Cc: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Subject: [FFmpeg-devel] [PATCH 5/9] avutil/buffer: Never poison returned buffers
Date: Tue,  9 Aug 2022 20:34:49 +0200
Message-ID: <DB6PR0101MB2214DDB8F9D6E0435D5773708F629@DB6PR0101MB2214.eurprd01.prod.exchangelabs.com> (raw)
In-Reply-To: <DB6PR0101MB22146E79DD73B701DA3549918F629@DB6PR0101MB2214.eurprd01.prod.exchangelabs.com>

Poisoning returned buffers is based around the implicit assumption
that the contents of said buffers are transient. Yet this is not true
for the buffer pools used by the various hardware contexts which store
important state in there that needs to be preserved.
Furthermore, the current code is also based on the assumption
that the complete buffer pointed to by AVBuffer->data coincides with
AVBufferRef->data; yet an implementation might store some data of its
own before the actual user-visible data (accessible via AVBufferRef)
which would be broken by the current code.

(This is of course yet more proof that the AVBuffer API is not the right
tool for the hardware contexts.)

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
I already sent this patch last October, but didn't apply it
due to lack of feedback. Future patches of mine depend upon
this and therefore I am sending it again.

 libavutil/buffer.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/libavutil/buffer.c b/libavutil/buffer.c
index 54590be566..e4562a79b1 100644
--- a/libavutil/buffer.c
+++ b/libavutil/buffer.c
@@ -341,9 +341,6 @@ static void pool_release_buffer(void *opaque, uint8_t *data)
     BufferPoolEntry *buf = opaque;
     AVBufferPool *pool = buf->pool;
 
-    if(CONFIG_MEMORY_POISONING)
-        memset(buf->data, FF_MEMORY_POISON, pool->size);
-
     ff_mutex_lock(&pool->mutex);
     buf->next = pool->pool;
     pool->pool = buf;
-- 
2.34.1

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  parent reply	other threads:[~2022-08-09 18:35 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-09 18:28 [FFmpeg-devel] [PATCH 1/9] avcodec/wmv2dec: Zero mb_type array for I pictures Andreas Rheinhardt
2022-08-09 18:34 ` [FFmpeg-devel] [PATCH 2/9] avcodec/mpegutils: Combine multiple av_log statements Andreas Rheinhardt
2022-08-09 18:34 ` [FFmpeg-devel] [PATCH 3/9] avcodec/mpegutils: Constify ff_print_debug_info2, ff_draw_horiz_band Andreas Rheinhardt
2022-08-09 18:34 ` [FFmpeg-devel] [PATCH 4/9] avcodec/mpegpicture: Remove always-true checks Andreas Rheinhardt
2022-08-09 18:34 ` Andreas Rheinhardt [this message]
2022-08-09 18:34 ` [FFmpeg-devel] [PATCH 6/9] avcodec/mpegpicture: Move encoding_error and mb_var_sum to MpegEncCtx Andreas Rheinhardt
2022-08-09 18:34 ` [FFmpeg-devel] [PATCH 7/9] avcodec/mpegvideo_enc: Don't copy Picture unnecessarily Andreas Rheinhardt
2022-08-09 18:34 ` [FFmpeg-devel] [PATCH 8/9] avcodec/mpegvideo_enc: Remove redundant check Andreas Rheinhardt
2022-08-09 18:34 ` [FFmpeg-devel] [PATCH 9/9] avcodec/mpegvideo_enc: Remove redundant cast Andreas Rheinhardt
2022-08-09 19:55 ` [FFmpeg-devel] [PATCH 10/11] avcodec/mpegvideo: Move setting mb_height to ff_mpv_init_context_frame Andreas Rheinhardt
2022-08-09 19:55 ` [FFmpeg-devel] [PATCH 11/11] avcodec/mpegpicture: Always reset motion val buffer Andreas Rheinhardt
2022-08-11  8:05   ` Andreas Rheinhardt

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