Hi. This patch fixes a real problem on 3.8.x, .3.9.x. Possibly earlier stable lines too but I only tested on 3.8 and 3.9.
Upstream patch applies fine to 3.8 and 3.9 stable lines. Please add to the stable queue. Thanks. commit 60403f7a4d9368d187f79cba5e4672d01df37574 Author: Guenter Roeck <[email protected]> Date: Fri Apr 5 21:22:43 2013 -0700 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 <[email protected]> Signed-off-by: Guenter Roeck <[email protected]> Tested-by: Arkadiusz Miskiewicz <[email protected]> Signed-off-by: Wim Van Sebroeck <[email protected]> -- Arkadiusz Miśkiewicz, arekm / maven.pl -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
