| Message ID | 20201103065217.67876-2-wangwensheng4@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [-next,v2,1/2] watchdog: Clean up error handlings of __watchdog_register_device | expand |
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c index c73871f41142..5269761ba072 100644 --- a/drivers/watchdog/watchdog_core.c +++ b/drivers/watchdog/watchdog_core.c @@ -265,8 +265,12 @@ static int __watchdog_register_device(struct watchdog_device *wdd) } if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { - wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; + if (!wdd->ops->stop) { + ret = -EINVAL; + goto dev_unregister; + } + wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; ret = register_reboot_notifier(&wdd->reboot_nb); if (ret) { pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
A reboot notifier, which stops the WDT by calling the stop hook without any check, would be registered when we set WDOG_STOP_ON_REBOOT flag. Howerer we allow the WDT driver to omit the stop hook since commit "d0684c8a93549" ("watchdog: Make stop function optional") and provide a module parameter for user that controls the WDOG_STOP_ON_REBOOT flag in commit 9232c80659e94 ("watchdog: Add stop_on_reboot parameter to control reboot policy"). Together that commits make user potential to insert a watchdog driver that don't provide a stop hook but with the stop_on_reboot parameter set, then dereferencing of null pointer occurs on system reboot. Check the stop hook before registering the reboot notifier to fix the issue. Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com> --- drivers/watchdog/watchdog_core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)