Re: [FFmpeg-devel] [PATCH] avcodec/snowdec: Fix integer overflow before htaps check

[Michael Niedermayer]

On Mon, Jan 15, 2018 at 03:27:16AM +0100, Michael Niedermayer wrote:
> Fixes: runtime error: signed integer overflow: -1094995529 * 2 cannot be 
> represented in type 'int'
> Fixes: 4828/clusterfuzz-testcase-minimized-5100849937252352
> 
> Found-by: continuous fuzzing process 
> https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer 
> ---
>  libavcodec/snowdec.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

will apply

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[FFmpeg-devel] [PATCH] avcodec/snowdec: Fix integer overflow before htaps check

[Michael Niedermayer]

Fixes: runtime error: signed integer overflow: -1094995529 * 2 cannot be 
represented in type 'int'
Fixes: 4828/clusterfuzz-testcase-minimized-5100849937252352

Found-by: continuous fuzzing process 
https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer 
---
 libavcodec/snowdec.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libavcodec/snowdec.c b/libavcodec/snowdec.c
index a9bdb8da5e..0146a2a4c9 100644
--- a/libavcodec/snowdec.c
+++ b/libavcodec/snowdec.c
@@ -363,9 +363,10 @@ static int decode_header(SnowContext *s){
 int htaps, i, sum=0;
 Plane *p= >plane[plane_index];
 p->diag_mc= get_rac(>c, s->header_state);
-htaps= get_symbol(>c, s->header_state, 0)*2 + 2;
-if((unsigned)htaps >= HTAPS_MAX || htaps==0)
+htaps= get_symbol(>c, s->header_state, 0);
+if((unsigned)htaps >= HTAPS_MAX/2 - 1)
 return AVERROR_INVALIDDATA;
+htaps = htaps*2 + 2;
 p->htaps= htaps;
 for(i= htaps/2; i; i--){
 p->hcoeff[i]= get_symbol(>c, s->header_state, 0) * 
(1-2*(i&1));
-- 
2.15.1

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