netdev - [PATCH -next] atm: iphase: fix possible use-after-free in ia_module

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Date:   Tue, 11 May 2021 14:53:36 +0800
From:   Zou Wei <zou_wei@...wei.com>
To:     <3chas3@...il.com>
CC:     <linux-atm-general@...ts.sourceforge.net>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Zou Wei <zou_wei@...wei.com>
Subject: [PATCH -next] atm: iphase: fix possible use-after-free in ia_module_exit()

This module's remove path calls del_timer(). However, that function
does not wait until the timer handler finishes. This means that the
timer handler may still be running after the driver's remove function
has finished, which would result in a use-after-free.

Fix by calling del_timer_sync(), which makes sure the timer handler
has finished, and unable to re-schedule itself.

Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Zou Wei <zou_wei@...wei.com>
---
 drivers/atm/iphase.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/atm/iphase.c b/drivers/atm/iphase.c
index 933e3ff..3f2ebfb 100644
--- a/drivers/atm/iphase.c
+++ b/drivers/atm/iphase.c
@@ -3279,7 +3279,7 @@ static void __exit ia_module_exit(void)
 {
 	pci_unregister_driver(&ia_driver);

-        del_timer(&ia_timer);
+	del_timer_sync(&ia_timer);
 }

 module_init(ia_module_init);
-- 
2.6.2