[S390] cio: fix wrong buffer access in cio_ignore_write

Writing only spaces to /proc/cio_ignore will cause a buffer overflow
since the size_t value i will not become negative and so buf[-1UL] is
accessed. Change the value of i to ssize_t.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/s390/cio/blacklist.c b/drivers/s390/cio/blacklist.c
index fe00be3675c..6565f027791 100644
--- a/drivers/s390/cio/blacklist.c
+++ b/drivers/s390/cio/blacklist.c
@@ -336,8 +336,7 @@ cio_ignore_write(struct file *file, const char __user *user_buf,
                  size_t user_len, loff_t *offset)
 {
         char *buf;
-        size_t i;
-        ssize_t rc, ret;
+        ssize_t rc, ret, i;
 
         if (*offset)
                 return -EINVAL;