From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Jerome Marchand <jmarchan@xxxxxxxxxx>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN drivers/block/zram/zram_drv.c~zram-fix-race-between-reset-and-flushing-pending-work drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-fix-race-between-reset-and-flushing-pending-work
+++ a/drivers/block/zram/zram_drv.c
@@ -553,14 +553,14 @@ static void zram_reset_device(struct zra
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;
_
--
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