diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index d058584b8f05..77738900e75e 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -5405,7 +5405,7 @@ int posix_info_sid_size(const void *beg, const void *end)
 	size_t subauth;
 	int total;
 
-	if (beg + 1 > end)
+	if (beg + 2 > end)
 		return -1;
 
 	subauth = *(u8 *)(beg+1);