[FFmpeg-cvslog] gifdec: refactor interleave end handling
Michael Niedermayer
git at videolan.org
Sat Dec 20 13:21:57 CET 2014
ffmpeg | branch: release/2.2 | Michael Niedermayer <michaelni at gmx.at> | Fri Oct 3 20:15:52 2014 +0200| [92888e9ed4ea4e761ae953bbe28c85cc658abc8f] | committer: Anton Khirnov
gifdec: refactor interleave end handling
Fixes invalid writes with very small image heights.
CC: libav-stable at libav.org
Bug-ID: CVE-2014-8547
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Anton Khirnov <anton at khirnov.net>
(cherry picked from commit 0b39ac6f54505a538c21fe49a626de94c518c903)
Signed-off-by: Anton Khirnov <anton at khirnov.net>
(cherry picked from commit eac49477aa95cf727d87d2741ee8e60be59d394b)
Signed-off-by: Anton Khirnov <anton at khirnov.net>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=92888e9ed4ea4e761ae953bbe28c85cc658abc8f
---
libavcodec/gifdec.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
diff --git a/libavcodec/gifdec.c b/libavcodec/gifdec.c
index cdb7f23..df5ab78 100644
--- a/libavcodec/gifdec.c
+++ b/libavcodec/gifdec.c
@@ -125,26 +125,21 @@ static int gif_read_image(GifState *s, AVFrame *frame)
case 1:
y1 += 8;
ptr += linesize * 8;
- if (y1 >= height) {
- y1 = pass ? 2 : 4;
- ptr = ptr1 + linesize * y1;
- pass++;
- }
break;
case 2:
y1 += 4;
ptr += linesize * 4;
- if (y1 >= height) {
- y1 = 1;
- ptr = ptr1 + linesize;
- pass++;
- }
break;
case 3:
y1 += 2;
ptr += linesize * 2;
break;
}
+ while (y1 >= height) {
+ y1 = 4 >> pass;
+ ptr = ptr1 + linesize * y1;
+ pass++;
+ }
} else {
ptr += linesize;
}
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