[FFmpeg-devel] [PATCH] jvdec: avoid unsized overflow in comparison

[Andreas Cadhalpun]

The return type of strlen is size_t, i.e. unsigned, so if pd->buf_size
is 3, the right side overflows leading to a wrong result of the
comparison and subsequently a heap buffer overflow.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
---
 libavformat/jvdec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/jvdec.c b/libavformat/jvdec.c
index 4d4f0c7..a31c723 100644
--- a/libavformat/jvdec.c
+++ b/libavformat/jvdec.c
@@ -54,7 +54,7 @@ typedef struct JVDemuxContext {
 
 static int read_probe(AVProbeData *pd)
 {
-    if (pd->buf[0] == 'J' && pd->buf[1] == 'V' && strlen(MAGIC) <= pd->buf_size - 4 &&
+    if (pd->buf[0] == 'J' && pd->buf[1] == 'V' && strlen(MAGIC) + 4 <= pd->buf_size &&
         !memcmp(pd->buf + 4, MAGIC, strlen(MAGIC)))
         return AVPROBE_SCORE_MAX;
     return 0;
-- 
2.6.1