The existing check has two problems:
1) i + count can overflow, so that the check '< 256' returns true.
2) In the (i == 'N') case occurs a j-- so that the loop runs once more.
This can trigger the assertion 'nut->header_len[0] == 0' or cause
segmentation faults or infinite hangs.
Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com>
---
libavformat/nutdec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libavformat/nutdec.c b/libavformat/nutdec.c
index 1bb2091..46946d3 100644
--- a/libavformat/nutdec.c
+++ b/libavformat/nutdec.c
@@ -294,7 +294,7 @@ static int decode_main_header(NUTContext *nut)
while (tmp_fields-- > 8)
ffio_read_varlen(bc);
- if (count == 0 || i + count > 256) {
+ if (count <= 0 || (i > 'N' && count > 256 - i) || (i <= 'N' && count >
255 - i)) {
av_log(s, AV_LOG_ERROR, "illegal count %d at %d\n", count, i);
return AVERROR_INVALIDDATA;
}
--
2.1.4
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