[FFmpeg-cvslog] avutil/common: Fix undefined behavior in av_clip_uintp2_c()

[Michael Niedermayer]

ffmpeg | branch: release/4.0 | Michael Niedermayer <michael at niedermayer.cc> | Thu Jun 14 15:41:33 2018 +0200| [9eaf9088978acecb32dd70a994d4a244ce9b1c59] | committer: Michael Niedermayer

avutil/common: Fix undefined behavior in av_clip_uintp2_c()

Fixes: negation of -2147483648 cannot be represented in type 'int'; cast to an unsigned type to negate this value to itself
Fixes: 8521/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DIRAC_fuzzer-5639024952737792

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit aa41d322be71106ce147445f2b42bb763f1eff86)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9eaf9088978acecb32dd70a994d4a244ce9b1c59
---

 libavutil/common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavutil/common.h b/libavutil/common.h
index 0fffa67714..8db0291170 100644
--- a/libavutil/common.h
+++ b/libavutil/common.h
@@ -228,7 +228,7 @@ static av_always_inline av_const int av_clip_intp2_c(int a, int p)
  */
 static av_always_inline av_const unsigned av_clip_uintp2_c(int a, int p)
 {
-    if (a & ~((1<<p) - 1)) return -a >> 31 & ((1<<p) - 1);
+    if (a & ~((1<<p) - 1)) return (~a) >> 31 & ((1<<p) - 1);
     else                   return  a;
 }