zram: fix race between reset and flushing pending work

Dan and Sergey reported that there is a racy between reset and flushing
of pending work so that it could make oops by freeing zram->meta in
reset while zram_slot_free can access zram->meta if new request is
adding during the race window.

This patch moves flush after taking init_lock so it prevents new request
so that it closes the race.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Minchan Kim 2014-01-30 15:45:58 -08:00 committed by Linus Torvalds
parent eae70d0684
commit da4a04126b

View File

@ -553,14 +553,14 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
size_t index;
struct zram_meta *meta;
flush_work(&zram->free_work);
down_write(&zram->init_lock);
if (!zram->init_done) {
up_write(&zram->init_lock);
return;
}
flush_work(&zram->free_work);
meta = zram->meta;
zram->init_done = 0;