[opus] [PATCH] op_fetch_and_process_page: fix int64 overflow

[James Zern]

check for overflow with a negative diff
---
 src/opusfile.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/opusfile.c b/src/opusfile.c
index 140503e..8b000a2 100644
--- a/src/opusfile.c
+++ b/src/opusfile.c
@@ -2078,7 +2078,11 @@ static int op_fetch_and_process_page(OggOpusFile *_of,
          &&OP_LIKELY(diff<total_duration)){
           cur_packet_gp=prev_packet_gp;
           for(pi=0;pi<op_count;pi++){
-            diff=durations[pi]-diff;
+            /*Check for overflow.*/
+            if(diff<0&&OP_UNLIKELY(OP_INT64_MAX+diff<durations[pi])){
+              diff=durations[pi]+1;
+            }
+            else diff=durations[pi]-diff;
             /*If we have samples to trim...*/
             if(diff>0){
               /*If we trimmed the entire packet, stop (the spec says encoders
-- 
2.15.1.424.g9478a66081-goog