UBI: fix leak in ubi_scan_erase_peb

Coverity (1769) found the following problem: if the erase counter
overflow check triggers, ec_hdr is leaked.

Moving the allocation after the overflow check should take care of it.
Signed-off-by: NFlorin Malita <fmalita@gmail.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>

drivers/mtd/ubi/scan.c

@@ -673,10 +673,6 @@ int ubi_scan_erase_peb(const struct ubi_device *ubi,
 	int err;
 	struct ubi_ec_hdr *ec_hdr;
 
-	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
-	if (!ec_hdr)
-		return -ENOMEM;
-
 	if ((long long)ec >= UBI_MAX_ERASECOUNTER) {
 		/*
 		 * Erase counter overflow. Upgrade UBI and use 64-bit
@@ -686,6 +682,10 @@ int ubi_scan_erase_peb(const struct ubi_device *ubi,
 		return -EINVAL;
 	}
 
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ec_hdr)
+		return -ENOMEM;
+
 	ec_hdr->ec = cpu_to_be64(ec);
 
 	err = ubi_io_sync_erase(ubi, pnum, 0);