[patch] mtd: sm_ftl: heap corruption in sm_create_sysfs_attributes()

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

We always put a NUL terminator one space past the end of the "vendor"
buffer.  Also I think the strnlen() limiter is off by one so I have made
it smaller.

Fixes: 7d17c02a01a1 ('mtd: Add new SmartMedia/xD FTL')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
Static analysis stuff.  Untested.

diff --git a/drivers/mtd/sm_ftl.c b/drivers/mtd/sm_ftl.c
index 4b8e89583f2a..7c452714df8d 100644
--- a/drivers/mtd/sm_ftl.c
+++ b/drivers/mtd/sm_ftl.c
@@ -59,11 +59,12 @@ static struct attribute_group *sm_create_sysfs_attributes(struct sm_ftl *ftl)
 	struct attribute_group *attr_group;
 	struct attribute **attributes;
 	struct sm_sysfs_attribute *vendor_attribute;
+	int vendor_len;
+	char *vendor;
 
-	int vendor_len = strnlen(ftl->cis_buffer + SM_CIS_VENDOR_OFFSET,
-					SM_SMALL_PAGE - SM_CIS_VENDOR_OFFSET);
-
-	char *vendor = kmalloc(vendor_len, GFP_KERNEL);
+	vendor_len = strnlen(ftl->cis_buffer + SM_CIS_VENDOR_OFFSET,
+			     SM_SMALL_PAGE - SM_CIS_VENDOR_OFFSET - 1);
+	vendor = kmalloc(vendor_len + 1, GFP_KERNEL);
 	if (!vendor)
 		goto error1;
 	memcpy(vendor, ftl->cis_buffer + SM_CIS_VENDOR_OFFSET, vendor_len);