[FFmpeg-devel] [PATCH 3/5] avcodec/vp9dsp_template: Fix integer overflows in idct16_1d()

[Michael Niedermayer]

Fixes: signed integer overflow: -190760 * 11585 cannot be represented in type 'int'
Fixes: 25471/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP9_fuzzer-5743354917421056

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/vp9dsp_template.c | 52 ++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 26 deletions(-)

diff --git a/libavcodec/vp9dsp_template.c b/libavcodec/vp9dsp_template.c
index 8d00e77d70..bfabe63536 100644
--- a/libavcodec/vp9dsp_template.c
+++ b/libavcodec/vp9dsp_template.c
@@ -1290,22 +1290,22 @@ static av_always_inline void idct16_1d(const dctcoef *in, ptrdiff_t stride,
     dctint t0a, t1a, t2a, t3a, t4a, t5a, t6a, t7a;
     dctint t8a, t9a, t10a, t11a, t12a, t13a, t14a, t15a;
 
-    t0a  = ((IN(0) + IN(8)) * 11585 + (1 << 13)) >> 14;
-    t1a  = ((IN(0) - IN(8)) * 11585 + (1 << 13)) >> 14;
-    t2a  = (IN(4)  *  6270 - IN(12) * 15137 + (1 << 13)) >> 14;
-    t3a  = (IN(4)  * 15137 + IN(12) *  6270 + (1 << 13)) >> 14;
-    t4a  = (IN(2)  *  3196 - IN(14) * 16069 + (1 << 13)) >> 14;
-    t7a  = (IN(2)  * 16069 + IN(14) *  3196 + (1 << 13)) >> 14;
-    t5a  = (IN(10) * 13623 - IN(6)  *  9102 + (1 << 13)) >> 14;
-    t6a  = (IN(10) *  9102 + IN(6)  * 13623 + (1 << 13)) >> 14;
-    t8a  = (IN(1)  *  1606 - IN(15) * 16305 + (1 << 13)) >> 14;
-    t15a = (IN(1)  * 16305 + IN(15) *  1606 + (1 << 13)) >> 14;
-    t9a  = (IN(9)  * 12665 - IN(7)  * 10394 + (1 << 13)) >> 14;
-    t14a = (IN(9)  * 10394 + IN(7)  * 12665 + (1 << 13)) >> 14;
-    t10a = (IN(5)  *  7723 - IN(11) * 14449 + (1 << 13)) >> 14;
-    t13a = (IN(5)  * 14449 + IN(11) *  7723 + (1 << 13)) >> 14;
-    t11a = (IN(13) * 15679 - IN(3)  *  4756 + (1 << 13)) >> 14;
-    t12a = (IN(13) *  4756 + IN(3)  * 15679 + (1 << 13)) >> 14;
+    t0a  = (dctint)((IN(0) + IN(8)) * 11585U + (1 << 13)) >> 14;
+    t1a  = (dctint)((IN(0) - IN(8)) * 11585U + (1 << 13)) >> 14;
+    t2a  = (dctint)(IN(4)  *  6270U - IN(12) * 15137U + (1 << 13)) >> 14;
+    t3a  = (dctint)(IN(4)  * 15137U + IN(12) *  6270U + (1 << 13)) >> 14;
+    t4a  = (dctint)(IN(2)  *  3196U - IN(14) * 16069U + (1 << 13)) >> 14;
+    t7a  = (dctint)(IN(2)  * 16069U + IN(14) *  3196U + (1 << 13)) >> 14;
+    t5a  = (dctint)(IN(10) * 13623U - IN(6)  *  9102U + (1 << 13)) >> 14;
+    t6a  = (dctint)(IN(10) *  9102U + IN(6)  * 13623U + (1 << 13)) >> 14;
+    t8a  = (dctint)(IN(1)  *  1606U - IN(15) * 16305U + (1 << 13)) >> 14;
+    t15a = (dctint)(IN(1)  * 16305U + IN(15) *  1606U + (1 << 13)) >> 14;
+    t9a  = (dctint)(IN(9)  * 12665U - IN(7)  * 10394U + (1 << 13)) >> 14;
+    t14a = (dctint)(IN(9)  * 10394U + IN(7)  * 12665U + (1 << 13)) >> 14;
+    t10a = (dctint)(IN(5)  *  7723U - IN(11) * 14449U + (1 << 13)) >> 14;
+    t13a = (dctint)(IN(5)  * 14449U + IN(11) *  7723U + (1 << 13)) >> 14;
+    t11a = (dctint)(IN(13) * 15679U - IN(3)  *  4756U + (1 << 13)) >> 14;
+    t12a = (dctint)(IN(13) *  4756U + IN(3)  * 15679U + (1 << 13)) >> 14;
 
     t0  = t0a  + t3a;
     t1  = t1a  + t2a;
@@ -1324,12 +1324,12 @@ static av_always_inline void idct16_1d(const dctcoef *in, ptrdiff_t stride,
     t14 = t15a - t14a;
     t15 = t15a + t14a;
 
-    t5a  = ((t6 - t5) * 11585 + (1 << 13)) >> 14;
-    t6a  = ((t6 + t5) * 11585 + (1 << 13)) >> 14;
-    t9a  = (  t14 *  6270 - t9  * 15137  + (1 << 13)) >> 14;
-    t14a = (  t14 * 15137 + t9  *  6270  + (1 << 13)) >> 14;
-    t10a = (-(t13 * 15137 + t10 *  6270) + (1 << 13)) >> 14;
-    t13a = (  t13 *  6270 - t10 * 15137  + (1 << 13)) >> 14;
+    t5a  = (dctint)((t6 - t5) * 11585U + (1 << 13)) >> 14;
+    t6a  = (dctint)((t6 + t5) * 11585U + (1 << 13)) >> 14;
+    t9a  = (dctint)(  t14 *  6270U - t9  * 15137U  + (1 << 13)) >> 14;
+    t14a = (dctint)(  t14 * 15137U + t9  *  6270U  + (1 << 13)) >> 14;
+    t10a = (dctint)(-(t13 * 15137U + t10 *  6270U) + (1 << 13)) >> 14;
+    t13a = (dctint)(  t13 *  6270U - t10 * 15137U  + (1 << 13)) >> 14;
 
     t0a  = t0   + t7;
     t1a  = t1   + t6a;
@@ -1348,10 +1348,10 @@ static av_always_inline void idct16_1d(const dctcoef *in, ptrdiff_t stride,
     t14  = t14a + t13a;
     t15a = t15  + t12;
 
-    t10a = ((t13  - t10)  * 11585 + (1 << 13)) >> 14;
-    t13a = ((t13  + t10)  * 11585 + (1 << 13)) >> 14;
-    t11  = ((t12a - t11a) * 11585 + (1 << 13)) >> 14;
-    t12  = ((t12a + t11a) * 11585 + (1 << 13)) >> 14;
+    t10a = (dctint)((t13  - t10)  * 11585U + (1 << 13)) >> 14;
+    t13a = (dctint)((t13  + t10)  * 11585U + (1 << 13)) >> 14;
+    t11  = (dctint)((t12a - t11a) * 11585U + (1 << 13)) >> 14;
+    t12  = (dctint)((t12a + t11a) * 11585U + (1 << 13)) >> 14;
 
     out[ 0] = t0a + t15a;
     out[ 1] = t1a + t14;
-- 
2.17.1