Patch "atm: iphase: fix possible use-after-free in ia_module_exit()" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     atm-iphase-fix-possible-use-after-free-in-ia_module_.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5fcfe9f625bc904cc7c33355de479273f297be21
Author: Zou Wei <zou_wei@xxxxxxxxxx>
Date:   Tue May 11 14:53:36 2021 +0800

    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@xxxxxxxxxx>
    Signed-off-by: Zou Wei <zou_wei@xxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/atm/iphase.c b/drivers/atm/iphase.c
index 8c7a996d1f16..46990352b5d3 100644
--- a/drivers/atm/iphase.c
+++ b/drivers/atm/iphase.c
@@ -3295,7 +3295,7 @@ 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);