fix server crash for STRALGO command

Author: hwware

src/t_string.c

@@ -519,15 +519,15 @@ void stralgoLCS(client *c) {
                 != C_OK) return;
             if (minmatchlen < 0) minmatchlen = 0;
             j++;
-        } else if (!strcasecmp(opt,"STRINGS")) {
+        } else if (!strcasecmp(opt,"STRINGS") && (c->argc-j) > 2) {
             if (a != NULL) {
                 addReplyError(c,"Either use STRINGS or KEYS");
                 return;
             }
             a = c->argv[j+1]->ptr;
             b = c->argv[j+2]->ptr;
             j += 2;
-        } else if (!strcasecmp(opt,"KEYS")) {
+        } else if (!strcasecmp(opt,"KEYS") && (c->argc-j) > 2) {
             if (a != NULL) {
                 addReplyError(c,"Either use STRINGS or KEYS");
                 return;