linux-kernel - [PATCH 4.7 086/141] mailbox: mailbox-test: set tdev->signal to NULL after freeing

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Date:   Thu,  6 Oct 2016 10:28:42 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sudeep Holla <sudeep.holla@....com>,
        Lee Jones <lee.jones@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: [PATCH 4.7 086/141] mailbox: mailbox-test: set tdev->signal to NULL after freeing

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sudeep Holla <sudeep.holla@....com>

commit 9ef3c5112139cc5c5666ee096e05bc1e00e94015 upstream.

tdev->signal is not set NULL after it's freed. This will cause random
exceptions when the stale pointer is accessed after tdev->signal is
freed. Also, since tdev->signal allocation is skipped the next time
it's written, this leads to continuous fault finally leading to the
total death of the system.

Fixes: d1c2f87c9a8f ("mailbox: mailbox-test: Prevent memory leak")
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Acked-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/mailbox/mailbox-test.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/mailbox/mailbox-test.c
+++ b/drivers/mailbox/mailbox-test.c
@@ -133,6 +133,7 @@ static ssize_t mbox_test_message_write(s
 out:
 	kfree(tdev->signal);
 	kfree(tdev->message);
+	tdev->signal = NULL;
 
 	return ret < 0 ? ret : count;
 }