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| author | Guenter Roeck <linux@roeck-us.net> | 2013-04-05 21:22:43 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-05-19 11:38:40 -0700 |
| commit | 5901e0b54b6bc78f731924a1f38826ce9e9d6fc6 (patch) | |
| tree | 6bfa89a5c7cf0f3563eaa1582fa3e901ca1eb7d1 /drivers/block/drbd/drbd_receiver.c | |
| parent | 59df3520db0cd2d5e35e4d79c03bd32d91812276 (diff) | |
watchdog: Fix race condition in registration code
commit 60403f7a4d9368d187f79cba5e4672d01df37574 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/block/drbd/drbd_receiver.c')
0 files changed, 0 insertions, 0 deletions