[patch] DM RAID: fix a couple integer overflows

[Dan Carpenter <dan.carpenter@oracle.com>]

My static checker complains that if "num_raid_params" is UINT_MAX then
the "if (num_raid_params + 1 > argc) {" check doesn't work as intended.

The other change is that I moved the "if (argc != (num_raid_devs * 2))"
condition forward a few lines so it was before the call to
context_alloc().  If we had an integer overflow inside that function
then it would lead to an immediate crash.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
Static checker stuff.  Not tested.

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 4880b69..e0d53fe 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1189,7 +1189,7 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	argv++;
 
 	/* Skip over RAID params for now and find out # of devices */
-	if (num_raid_params + 1 > argc) {
+	if (num_raid_params >= argc) {
 		ti->error = "Arguments do not agree with counts given";
 		return -EINVAL;
 	}
@@ -1200,6 +1200,12 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 		return -EINVAL;
 	}
 
+	argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */
+	if (argc != (num_raid_devs * 2)) {
+		ti->error = "Supplied RAID devices does not match the count given";
+		return -EINVAL;
+	}
+
 	rs = context_alloc(ti, rt, (unsigned)num_raid_devs);
 	if (IS_ERR(rs))
 		return PTR_ERR(rs);
@@ -1208,16 +1214,8 @@ static int raid_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	if (ret)
 		goto bad;
 
-	ret = -EINVAL;
-
-	argc -= num_raid_params + 1; /* +1: we already have num_raid_devs */
 	argv += num_raid_params + 1;
 
-	if (argc != (num_raid_devs * 2)) {
-		ti->error = "Supplied RAID devices does not match the count given";
-		goto bad;
-	}
-
 	ret = dev_parms(rs, argv);
 	if (ret)
 		goto bad;