Make sure we never underflow len in DetectLoadSigFile

diff --git a/src/detect.c b/src/detect.c
index 8e70d83520f8e1042dcfd636bec9f4335a6de6e6..67104d72ca67c3dadaa30493b7dc5d5f641b5f81 100644 (file)
--- a/src/detect.c
+++ b/src/detect.c
@@ -526,7 +526,7 @@ int DetectLoadSigFile(DetectEngineCtx *de_ctx, char *sig_file, int *sigs_tot) {
             continue;
 
         /* Check for multiline rules. */
-        while (isspace(line[--len]));
+        while (len > 0 && isspace(line[--len]));
         if (line[len] == '\\') {
             multiline++;
             offset = len;