[PATCH AUTOSEL 4.14 7/9] drivers:md:fix a potential use-after-free bug

Sasha Levin
2022-08-14T15:52:40Z

From: Wentao_Liang <Wentao_Liang_g@163.com>

[ Upstream commit 104212471b1c1817b311771d817fb692af983173 ]

In line 2884, "raid5_release_stripe(sh);" drops the reference to sh and
may cause sh to be released. However, sh is subsequently used in lines
2886 "if (sh->batch_head && sh != sh->batch_head)". This may result in an
use-after-free bug.

It can be fixed by moving "raid5_release_stripe(sh);" to the bottom of
the function.

Signed-off-by: Wentao_Liang <Wentao_Liang_g@163.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/raid5.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 1e52443f3aca..866ba1743f9f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2668,10 +2668,10 @@ static void raid5_end_write_request(struct bio *bi)
if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
clear_bit(R5_LOCKED, &sh->dev[i].flags);
set_bit(STRIPE_HANDLE, &sh->state);
- raid5_release_stripe(sh);

if (sh->batch_head && sh != sh->batch_head)
raid5_release_stripe(sh->batch_head);
+ raid5_release_stripe(sh);
}

static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
--
2.35.1