This is a note to let you know that I've just added the patch titled
mailbox: mailbox-test: fix a locking issue in mbox_test_message_write()
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mailbox-mailbox-test-fix-a-locking-issue-in-mbox_tes.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5ac1fb76827e9d1126e1cd742aff7a619b9ff7f6
Author: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Date: Fri May 5 12:22:09 2023 +0300
mailbox: mailbox-test: fix a locking issue in mbox_test_message_write()
[ Upstream commit 8fe72b76db79d694858e872370df49676bc3be8c ]
There was a bug where this code forgot to unlock the tdev->mutex if the
kzalloc() failed. Fix this issue, by moving the allocation outside the
lock.
Fixes: 2d1e952a2b8e ("mailbox: mailbox-test: Fix potential double-free in mbox_test_message_write()")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: Lee Jones <lee@xxxxxxxxxx>
Signed-off-by: Jassi Brar <jaswinder.singh@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c
index c7ff9653223bf..39236030079e0 100644
--- a/drivers/mailbox/mailbox-test.c
+++ b/drivers/mailbox/mailbox-test.c
@@ -101,6 +101,7 @@ static ssize_t mbox_test_message_write(struct file *filp,
size_t count, loff_t *ppos)
{
struct mbox_test_device *tdev = filp->private_data;
+ char *message;
void *data;
int ret;
@@ -116,12 +117,13 @@ static ssize_t mbox_test_message_write(struct file *filp,
return -EINVAL;
}
- mutex_lock(&tdev->mutex);
-
- tdev->message = kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL);
- if (!tdev->message)
+ message = kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL);
+ if (!message)
return -ENOMEM;
+ mutex_lock(&tdev->mutex);
+
+ tdev->message = message;
ret = copy_from_user(tdev->message, userbuf, count);
if (ret) {
ret = -EFAULT;
