[PATCH 5.12 069/173] bus: mhi: pci_generic: Fix possible use-after-free in mhi_pci_remove()

[Greg Kroah-Hartman]

From: Wei Yongjun <weiyongjun1@xxxxxxxxxx>

commit 0b67808ade8893a1b3608ddd74fac7854786c919 upstream.

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.

Link: https://lore.kernel.org/r/20210413160318.2003699-1-weiyongjun1@xxxxxxxxxx
Fixes: 8562d4fe34a3 ("mhi: pci_generic: Add health-check")
Cc: stable <stable@xxxxxxxxxxxxxxx>
Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Reviewed-by: Hemant kumar <hemantk@xxxxxxxxxxxxxx>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Reviewed-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
Signed-off-by: Wei Yongjun <weiyongjun1@xxxxxxxxxx>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210606153741.20725-3-manivannan.sadhasivam@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/bus/mhi/pci_generic.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/bus/mhi/pci_generic.c
+++ b/drivers/bus/mhi/pci_generic.c
@@ -505,7 +505,7 @@ static void mhi_pci_remove(struct pci_de
 	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)) {