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

Message ID 20180115022716.29784-1-michael@niedermayer.cc
State Accepted
Commit 2eecf3cf8eeae67697934df326e98df2149881e5
Headers show

Commit Message

Michael Niedermayer Jan. 15, 2018, 2:27 a.m. UTC
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 <michael@niedermayer.cc>
---
 libavcodec/snowdec.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Michael Niedermayer Jan. 20, 2018, 2:18 a.m. UTC | #1
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 <michael@niedermayer.cc>
> ---
>  libavcodec/snowdec.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

will apply

[...]
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Patch

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= &s->plane[plane_index];
                 p->diag_mc= get_rac(&s->c, s->header_state);
-                htaps= get_symbol(&s->c, s->header_state, 0)*2 + 2;
-                if((unsigned)htaps >= HTAPS_MAX || htaps==0)
+                htaps= get_symbol(&s->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(&s->c, s->header_state, 0) * (1-2*(i&1));