hfs: add sanity check for file name length

On a corrupted file system the ->len field could be wrong leading to
a buffer overflow.

Reported-and-acked-by: Clement LECIGNE <clement.lecigne@netasq.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/hfs/trans.c b/fs/hfs/trans.c
index e673a88..b1ce4c7 100644
--- a/fs/hfs/trans.c
+++ b/fs/hfs/trans.c
@@ -40,6 +40,8 @@
 
 	src = in->name;
 	srclen = in->len;
+	if (srclen > HFS_NAMELEN)
+		srclen = HFS_NAMELEN;
 	dst = out;
 	dstlen = HFS_MAX_NAMELEN;
 	if (nls_io) {