avformat/avidec: Fix infinite loop in avi_read_nikon()

Fixes: 360/test.poc
Found-by: 连一汉 <lianyihan@360.cn>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/avidec.c

@@ -344,14 +344,14 @@ static void avi_metadata_creation_time(AVDictionary **metadata, char *date)
 
 static void avi_read_nikon(AVFormatContext *s, uint64_t end)
 {
-    while (avio_tell(s->pb) < end) {
+    while (avio_tell(s->pb) < end && !avio_feof(s->pb)) {
         uint32_t tag  = avio_rl32(s->pb);
         uint32_t size = avio_rl32(s->pb);
         switch (tag) {
         case MKTAG('n', 'c', 't', 'g'):  /* Nikon Tags */
         {
             uint64_t tag_end = avio_tell(s->pb) + size;
-            while (avio_tell(s->pb) < tag_end) {
+            while (avio_tell(s->pb) < tag_end && !avio_feof(s->pb)) {
                 uint16_t tag     = avio_rl16(s->pb);
                 uint16_t size    = avio_rl16(s->pb);
                 const char *name = NULL;