[FFmpeg-cvslog] avcodec/cbs_av1: Make overread check more robust

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at gmail.com> | Wed Sep 18 05:26:01 2019 +0200| [1929dd4eff93e81bab8637f298754294448e624e] | committer: Mark Thompson

avcodec/cbs_av1: Make overread check more robust

When performing a comparison of a signed int and an unsigned int, the
signed int is first converted to an unsigned int, so that negative
values are being treated as big, positive values. This can become a
problem in an overread check, namely when an overread already happened.
So change the type of the variable containing the amount of bits that
need to be left to signed.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1929dd4eff93e81bab8637f298754294448e624e
---

 libavcodec/cbs_av1.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/cbs_av1.c b/libavcodec/cbs_av1.c
index 98cd37ef74..c027933218 100644
--- a/libavcodec/cbs_av1.c
+++ b/libavcodec/cbs_av1.c
@@ -211,8 +211,8 @@ static int cbs_av1_read_ns(CodedBitstreamContext *ctx, GetBitContext *gbc,
                            uint32_t n, const char *name,
                            const int *subscripts, uint32_t *write_to)
 {
-    uint32_t w, m, v, extra_bit, value;
-    int position;
+    uint32_t m, v, extra_bit, value;
+    int position, w;
 
     av_assert0(n > 0);