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authorGuenter Roeck <linux@roeck-us.net>2013-04-06 04:22:43 (GMT)
committerWim Van Sebroeck <wim@iguana.be>2013-05-09 06:13:41 (GMT)
commit60403f7a4d9368d187f79cba5e4672d01df37574 (patch)
treec59fab4f8adfbe04244c1fd7bb7ff8073c29f65b /arch
parent6330c7070be6783b82025d2bc259db8413c00182 (diff)
downloadlinux-60403f7a4d9368d187f79cba5e4672d01df37574.tar.xz
watchdog: Fix race condition in registration code
A race condition exists when registering the first watchdog device. Sequence of events: - watchdog_register_device calls watchdog_dev_register - watchdog_dev_register creates the watchdog misc device by calling misc_register. At that time, the matching character device (/dev/watchdog0) does not yet exist, and old_wdd is not set either. - Userspace gets an event and opens /dev/watchdog - watchdog_open is called and sets wdd = old_wdd, which is still NULL, and tries to dereference it. This causes the kernel to panic. Seen with systemd trying to open /dev/watchdog immediately after it was created. Reported-by: Arkadiusz Miskiewicz <arekm@maven.pl> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Arkadiusz Miskiewicz <arekm@maven.pl> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Diffstat (limited to 'arch')
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