diff mbox series

[RESEND,v2] media: bttv: fix use after free error due to btv->timeout timer

Message ID 20230413034405.36037-1-zyytlz.wz@163.com
State Accepted
Commit bd5b50b329e850d467e7bcc07b2b6bde3752fbda
Headers show
Series [RESEND,v2] media: bttv: fix use after free error due to btv->timeout timer | expand

Commit Message

Zheng Wang April 13, 2023, 3:44 a.m. UTC
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

Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
---
v2:
- stop replacing del_timer with del_timer_sync suggested by Hillf Danton
---
 drivers/media/pci/bt8xx/bttv-driver.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/drivers/media/pci/bt8xx/bttv-driver.c b/drivers/media/pci/bt8xx/bttv-driver.c
index d40b537f4e98..24ba5729969d 100644
--- a/drivers/media/pci/bt8xx/bttv-driver.c
+++ b/drivers/media/pci/bt8xx/bttv-driver.c
@@ -4248,6 +4248,7 @@  static void bttv_remove(struct pci_dev *pci_dev)
 
 	/* free resources */
 	free_irq(btv->c.pci->irq,btv);
+	del_timer_sync(&btv->timeout);
 	iounmap(btv->bt848_mmio);
 	release_mem_region(pci_resource_start(btv->c.pci,0),
 			   pci_resource_len(btv->c.pci,0));