qemu-img: improve queue depth validation in img_bench

This error was discovered by fuzzing qemu-img.

Currently, running `qemu-img bench -d 0` in img_bench is allowed,
which is a pointless operation and causes qemu-img to hang.

Signed-off-by: Denis Rastyogin <gerben@altlinux.org>
Message-ID: <20250327162423.25154-5-gerben@altlinux.org>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

qemu-img.c

@@ -4571,7 +4571,7 @@ static int img_bench(int argc, char **argv)
         {
             unsigned long res;
 
-            if (qemu_strtoul(optarg, NULL, 0, &res) < 0 || res > INT_MAX) {
+            if (qemu_strtoul(optarg, NULL, 0, &res) <= 0 || res > INT_MAX) {
                 error_report("Invalid queue depth specified");
                 return 1;
             }