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watchdog: Fix potential dereferencing of null pointer
[ Upstream commit6f733cb2e7
] 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 commit9232c80659
("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. Fixes:d0684c8a93
("watchdog: Make stop function optional") Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20201109130512.28121-1-wangwensheng4@huawei.com Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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parent
4e091ff107
commit
d4dbcfb7e1
1 changed files with 12 additions and 8 deletions
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@ -255,15 +255,19 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
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}
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if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
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wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
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if (!wdd->ops->stop)
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pr_warn("watchdog%d: stop_on_reboot not supported\n", wdd->id);
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else {
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wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
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ret = register_reboot_notifier(&wdd->reboot_nb);
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if (ret) {
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pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
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wdd->id, ret);
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watchdog_dev_unregister(wdd);
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ida_simple_remove(&watchdog_ida, id);
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return ret;
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ret = register_reboot_notifier(&wdd->reboot_nb);
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if (ret) {
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pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
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wdd->id, ret);
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watchdog_dev_unregister(wdd);
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ida_simple_remove(&watchdog_ida, id);
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return ret;
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}
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}
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}
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