[PATCH 2/3] bus: mhi: pci_generic: Fix possible use-after-free in mhi_pci_remove()

[Manivannan Sadhasivam]

From: Wei Yongjun <weiyongjun1@xxxxxxxxxx>

This driver'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.

Fixes: 8562d4fe34a3 ("mhi: pci_generic: Add health-check")
Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Wei Yongjun <weiyongjun1@xxxxxxxxxx>
Reviewed-by: Hemant kumar <hemantk@xxxxxxxxxxxxxx>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Reviewed-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210413160318.2003699-1-weiyongjun1@xxxxxxxxxx
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
 drivers/bus/mhi/pci_generic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
index 8c7f6576e421..0a6619ad292c 100644
--- a/drivers/bus/mhi/pci_generic.c
+++ b/drivers/bus/mhi/pci_generic.c
@@ -708,7 +708,7 @@ static void mhi_pci_remove(struct pci_dev *pdev)
 	struct mhi_pci_device *mhi_pdev = pci_get_drvdata(pdev);
 	struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
 
-	del_timer(&mhi_pdev->health_check_timer);
+	del_timer_sync(&mhi_pdev->health_check_timer);
 	cancel_work_sync(&mhi_pdev->recovery_work);
 
 	if (test_and_clear_bit(MHI_PCI_DEV_STARTED, &mhi_pdev->status)) {
-- 
2.25.1