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>
(cherry picked from commit da4a04126baa3be03bc566d4a2ee0944c5e783d0)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index d66b404..1a37787 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -552,14 +552,14 @@
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;