[FFmpeg-cvslog] avcodec/av1dec: Fix resolving zero divisor

[Michael Niedermayer]

ffmpeg | branch: release/5.1 | Michael Niedermayer <michael at niedermayer.cc> | Thu Nov 30 02:36:41 2023 +0100| [7c4a401a925c878f0635b7abd240199a13c7d8c5] | committer: Michael Niedermayer

avcodec/av1dec: Fix resolving zero divisor

Fixes: Out of array read
Fixes: global-buffer-overflow-AV1

Found-by: "Leonelli, Matteo" <matteo.leonelli at cispa.de>
Tested-by: "Wang, Fei W" <fei.w.wang at intel.com>
Reviewed-by: "Wang, Fei W" <fei.w.wang at intel.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 22daf2148fc072f8f347af939f88b3af7896ab60)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7c4a401a925c878f0635b7abd240199a13c7d8c5
---

 libavcodec/av1dec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/av1dec.c b/libavcodec/av1dec.c
index 9cd5fcbb29..600b022626 100644
--- a/libavcodec/av1dec.c
+++ b/libavcodec/av1dec.c
@@ -170,7 +170,7 @@ static uint8_t get_shear_params_valid(AV1DecContext *s, int idx)
     int16_t alpha, beta, gamma, delta, divf, divs;
     int64_t v, w;
     int32_t *param = &s->cur_frame.gm_params[idx][0];
-    if (param[2] < 0)
+    if (param[2] <= 0)
         return 0;
 
     alpha = av_clip_int16(param[2] - (1 << AV1_WARPEDMODEL_PREC_BITS));