lzw: fix potential integer overflow.

diff --git a/libavcodec/lzw.c b/libavcodec/lzw.c
index b674d4e296bed64214bfdf9ef44b3690cbd23ade..8761510283556a7d804751f0eefd2dcadcbaac5c 100644 (file)
--- a/libavcodec/lzw.c
+++ b/libavcodec/lzw.c
@@ -102,7 +102,7 @@ void ff_lzw_decode_tail(LZWState *p)
 
     if(s->mode == FF_LZW_GIF) {
         while (s->bs > 0) {
-            if (s->pbuf + s->bs >= s->ebuf) {
+            if (s->bs >= s->ebuf - s->pbuf) {
                 s->pbuf = s->ebuf;
                 break;
             } else {