On 26.11.2016 01:53, Michael Niedermayer wrote:
> On Fri, Nov 25, 2016 at 10:13:06PM +0100, Andreas Cadhalpun wrote:
>> This fixes a segmentation fault caused by calling memcpy with NULL as
>> second argument in handle_p_frame_apng.
>>
>> Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
>> ---
>> libavcodec/pngdec.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
>> index 36275ae..a7b330b 100644
>> --- a/libavcodec/pngdec.c
>> +++ b/libavcodec/pngdec.c
>> @@ -922,7 +922,7 @@ static int decode_fctl_chunk(AVCodecContext *avctx,
>> PNGDecContext *s,
>> return AVERROR_INVALIDDATA;
>> }
>>
>> - if (sequence_number == 0 && dispose_op == APNG_DISPOSE_OP_PREVIOUS) {
>> + if (!s->previous_picture.f->data[0] && dispose_op ==
>> APNG_DISPOSE_OP_PREVIOUS) {
>> // No previous frame to revert to for the first frame
>> // Spec says to just treat it as a APNG_DISPOSE_OP_BACKGROUND
>> dispose_op = APNG_DISPOSE_OP_BACKGROUND;
>
> wont this be different when seeking back to the
> first frame ?
> is that intended ?
I don't think the apng demuxer supports seeking.
But it shouldn't hurt to check both sequence_number and the previous frame.
Updated patch is attached.
Best regards,
Andreas
>From 84125e5f32fd4b9146d9926d2f8a4467da7c8557 Mon Sep 17 00:00:00 2001
From: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
Date: Fri, 25 Nov 2016 22:09:51 +0100
Subject: [PATCH] pngdec: check if previous frame exists instead of trusting
sequence_number
This fixes a segmentation fault caused by calling memcpy with NULL as
second argument in handle_p_frame_apng.
Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
---
libavcodec/pngdec.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 36275ae..2f8d266 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -922,7 +922,8 @@ static int decode_fctl_chunk(AVCodecContext *avctx, PNGDecContext *s,
return AVERROR_INVALIDDATA;
}
- if (sequence_number == 0 && dispose_op == APNG_DISPOSE_OP_PREVIOUS) {
+ if ((sequence_number == 0 || !s->previous_picture.f->data[0]) &&
+ dispose_op == APNG_DISPOSE_OP_PREVIOUS) {
// No previous frame to revert to for the first frame
// Spec says to just treat it as a APNG_DISPOSE_OP_BACKGROUND
dispose_op = APNG_DISPOSE_OP_BACKGROUND;
--
2.10.2
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
