X-Git-Url: https://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/29ce214c65d0d36679b8496dd8dddf4ea2b0ec23..f7b4257301e2ff4b490ae84d0b8ecbe3c7dfe241:/common/lfdemod.c

diff --git a/common/lfdemod.c b/common/lfdemod.c
index 7e31f53d..f231cd69 100644
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -148,8 +148,11 @@ uint32_t bytebits_to_byteLSBF(uint8_t *src, size_t numbits)
 //search for given preamble in given BitStream and return success=1 or fail=0 and startIndex and length
 uint8_t preambleSearch(uint8_t *BitStream, uint8_t *preamble, size_t pLen, size_t *size, size_t *startIdx)
 {
-	uint8_t foundCnt=0;
-	for (int idx=0; idx < *size - pLen; idx++){
+	// Sanity check.  If preamble length is bigger than bitstream length.
+	if ( *size <= pLen ) return 0;
+	
+	uint8_t foundCnt = 0;
+	for (int idx = 0; idx < *size - pLen; idx++){
 		if (memcmp(BitStream+idx, preamble, pLen) == 0){
 			//first index found
 			foundCnt++;