[PATCH -next] atm: iphase: fix possible use-after-free in ia_module_exit()

[PATCH -next] atm: iphase: fix possible use-after-free in ia_module_exit()

[Zou Wei]

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>
---
 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

Re: [PATCH -next] atm: iphase: fix possible use-after-free in ia_module_exit()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Tue, 11 May 2021 14:53:36 +0800 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [-next] atm: iphase: fix possible use-after-free in ia_module_exit()
    https://git.kernel.org/netdev/net-next/c/1c72e6ab66b9

You are awesome, thank you!
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