media: bttv: fix use after free error due to btv->timeout timer
authorZheng Wang <zyytlz.wz@163.com>
Thu, 13 Apr 2023 03:49:42 +0000 (11:49 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 20 Nov 2023 10:59:32 +0000 (11:59 +0100)
commit847599fffa528b2cdec4e21b6bf7586dad982132
tree8413a2931c479699a7757adeb4cfaf7adca14962
parentf9f6e9cb998543c2610e3ba134256666beda8036
media: bttv: fix use after free error due to btv->timeout timer

[ Upstream commit bd5b50b329e850d467e7bcc07b2b6bde3752fbda ]

There may be some a race condition between timer function
bttv_irq_timeout and bttv_remove. The timer is setup in
probe and there is no timer_delete operation in remove
function. When it hit kfree btv, the function might still be
invoked, which will cause use after free bug.

This bug is found by static analysis, it may be false positive.

Fix it by adding del_timer_sync invoking to the remove function.

cpu0                cpu1
                  bttv_probe
                    ->timer_setup
                      ->bttv_set_dma
                        ->mod_timer;
bttv_remove
  ->kfree(btv);
                  ->bttv_irq_timeout
                    ->USE btv

Fixes: 162e6376ac58 ("media: pci: Convert timers to use timer_setup()")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/media/pci/bt8xx/bttv-driver.c