misc: ibmvsm: Fix potential NULL pointer dereference

commit e25df7812c91f62581301f9a7ac102acf92e4937 upstream.

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>

diff --git a/drivers/misc/ibmvmc.c b/drivers/misc/ibmvmc.c
index b8aaa68..2ed23c9 100644 (file)
--- 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;
 }
 
 /**