s390/dasd: fix Oops in dasd_alias_get_start_dev due to missing pavgroup
commit db7ba07108a48c0f95b74fabbfd5d63e924f992d upstream.
Fix Oops in dasd_alias_get_start_dev() function caused by the pavgroup
pointer being NULL.
The pavgroup pointer is checked on the entrance of the function but
without the lcu->lock being held. Therefore there is a race window
between dasd_alias_get_start_dev() and _lcu_update() which sets
pavgroup to NULL with the lcu->lock held.
Fix by checking the pavgroup pointer with lcu->lock held.
Cc: <[email protected]> # 2.6.25+
Fixes: 8e09f21574ea ("[S390] dasd: add hyper PAV support to DASD device driver, part 1")
Signed-off-by: Stefan Haberland <[email protected]>
Reviewed-by: Jan Hoeppner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
1 file changed
