From: Zou Wei <zou_wei@huawei.com>
Date: Tue, 11 May 2021 06:53:36 +0000 (+0800)
Subject: atm: iphase: fix possible use-after-free in ia_module_exit()
X-Git-Tag: v4.4.276~94
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9e161687855175334ca93c6c3ccb221731194479;p=thirdparty%2Fkernel%2Fstable.git

atm: iphase: fix possible use-after-free in ia_module_exit()

[ Upstream commit 1c72e6ab66b9598cac741ed397438a52065a8f1f ]

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@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/atm/iphase.c b/drivers/atm/iphase.c
index 860a33a90ebf8..dc1b7f11e6af5 100644
--- a/drivers/atm/iphase.c
+++ b/drivers/atm/iphase.c
@@ -3296,7 +3296,7 @@ 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);