From: Dan Carpenter <dan.carpenter@linaro.org>
Date: Fri, 5 May 2023 09:22:09 +0000 (+0300)
Subject: mailbox: mailbox-test: fix a locking issue in mbox_test_message_write()
X-Git-Tag: v5.4.246~40
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=030ca3f7b042964b37f39d5118fde50cbe9fd2d7;p=thirdparty%2Fkernel%2Fstable.git

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@linaro.org>
Reviewed-by: Lee Jones <lee@kernel.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c
index 6dd5b9614452b..abcee58e851c2 100644
--- a/drivers/mailbox/mailbox-test.c
+++ b/drivers/mailbox/mailbox-test.c
@@ -97,6 +97,7 @@ 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;
 
@@ -112,12 +113,13 @@ 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;