misc: ibmvsm: Fix potential NULL pointer dereference

There is a potential NULL pointer dereference in case kzalloc()
fails and returns NULL.

Fix this by adding a NULL check on *session*

Also, update the function header with information about the
expected return on failure and remove unnecessary variable rc.

This issue was detected with the help of Coccinelle.

Fixes: 0eca353e7ae7 ("misc: IBM Virtual Management Channel Driver (VMC)")
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/misc/ibmvmc.c b/drivers/misc/ibmvmc.c
index b8aaa684c397..2ed23c99f59f 100644
--- a/drivers/misc/ibmvmc.c
+++ b/drivers/misc/ibmvmc.c
@@ -820,21 +820,24 @@ static int ibmvmc_send_msg(struct crq_server_adapter *adapter,
  *
  * Return:
  *      0 - Success
+ *      Non-zero - Failure
  */
 static int ibmvmc_open(struct inode *inode, struct file *file)
 {
         struct ibmvmc_file_session *session;
-        int rc = 0;
 
         pr_debug("%s: inode = 0x%lx, file = 0x%lx, state = 0x%x\n", __func__,
                  (unsigned long)inode, (unsigned long)file,
                  ibmvmc.state);
 
         session = kzalloc(sizeof(*session), GFP_KERNEL);
+        if (!session)
+                return -ENOMEM;
+
         session->file = file;
         file->private_data = session;
 
-        return rc;
+        return 0;
 }
 
 /**