Messages in this thread Patch in this message | | | From | Duoming Zhou <> | Subject | [PATCH] mISDN: hfcpci: Fix use-after-free bug in hfcpci_softirq | Date | Sun, 9 Oct 2022 14:37:31 +0800 |
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The function hfcpci_softirq() is a timer handler. If it is running, the timer_pending() will return 0 and the del_timer_sync() in HFC_cleanup() will not be executed. As a result, the use-after-free bug will happen. The process is shown below:
(cleanup routine) | (timer handler) HFC_cleanup() | hfcpci_softirq() if (timer_pending(&hfc_tl)) | del_timer_sync() | ... | ... pci_unregister_driver(hc) | driver_unregister | driver_for_each_device bus_remove_driver | _hfcpci_softirq driver_detach | ... put_device(dev) //[1]FREE | | dev_get_drvdata(dev) //[2]USE
The device is deallocated is position [1] and used in position [2].
Fix by removing the "timer_pending" check in HFC_cleanup(), which makes sure that the hfcpci_softirq() have finished before the resource is deallocated.
Fixes: 009fc857c5f6 ("mISDN: fix possible use-after-free in HFC_cleanup()") Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- drivers/isdn/hardware/mISDN/hfcpci.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/isdn/hardware/mISDN/hfcpci.c b/drivers/isdn/hardware/mISDN/hfcpci.c index af17459c1a5..e964a8dd851 100644 --- a/drivers/isdn/hardware/mISDN/hfcpci.c +++ b/drivers/isdn/hardware/mISDN/hfcpci.c @@ -2345,8 +2345,7 @@ HFC_init(void) static void __exit HFC_cleanup(void) { - if (timer_pending(&hfc_tl)) - del_timer_sync(&hfc_tl); + del_timer_sync(&hfc_tl); pci_unregister_driver(&hfc_driver); } -- 2.17.1
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