SCAN requires at least 1 argument

src/db.c

@@ -327,6 +327,8 @@ void scanCommand(redisClient *c) {
     sds pat;
     int patlen, patnoop = 1;
 
+    redisAssert(c->argc >= 2);
+
     /* Use sscanf because we need an *unsigned* long */
     rv = sscanf(c->argv[1]->ptr, "%lu", &cursor);
     if (rv != 1) {

src/redis.c

@@ -207,7 +207,7 @@ struct redisCommand redisCommandTable[] = {
     {"pexpire",pexpireCommand,3,"w",0,NULL,1,1,1,0,0},
     {"pexpireat",pexpireatCommand,3,"w",0,NULL,1,1,1,0,0},
     {"keys",keysCommand,2,"rS",0,NULL,0,0,0,0,0},
-    {"scan",scanCommand,-1,"RS",0,NULL,0,0,0,0,0},
+    {"scan",scanCommand,-2,"RS",0,NULL,0,0,0,0,0},
     {"dbsize",dbsizeCommand,1,"r",0,NULL,0,0,0,0,0},
     {"auth",authCommand,2,"rslt",0,NULL,0,0,0,0,0},
     {"ping",pingCommand,1,"rt",0,NULL,0,0,0,0,0},