[PATCH] dm raid: add missed unlock in raid_ctr

[PATCH] dm raid: add missed unlock in raid_ctr

[Dinghao Liu]

mddev_unlock() is called on all paths after we call mddev_lock_nointr(),
except for three error handling paths, which may cause a deadlock. This
bug is suggested by a static analysis tool, please advise.

Fixes: 9dbd1aa3a81c ("dm raid: add reshaping support to the target")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
---
 drivers/md/dm-raid.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index d9ef52159a22..79f36a806082 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3276,15 +3276,19 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	/* Try to adjust the raid4/5/6 stripe cache size to the stripe size */
 	if (rs_is_raid456(rs)) {
 		r = rs_set_raid456_stripe_cache(rs);
-		if (r)
+		if (r) {
+			mddev_unlock(&rs->md);
 			goto bad_stripe_cache;
+		}
 	}
 
 	/* Now do an early reshape check */
 	if (test_bit(RT_FLAG_RESHAPE_RS, &rs->runtime_flags)) {
 		r = rs_check_reshape(rs);
-		if (r)
+		if (r) {
+			mddev_unlock(&rs->md);
 			goto bad_check_reshape;
+		}
 
 		/* Restore new, ctr requested layout to perform check */
 		rs_config_restore(rs, &rs_layout);
@@ -3293,6 +3297,7 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 			r = rs->md.pers->check_reshape(&rs->md);
 			if (r) {
 				ti->error = "Reshape check failed";
+				mddev_unlock(&rs->md);
 				goto bad_check_reshape;
 			}
 		}
-- 
2.17.1

Re: Re: [PATCH] dm raid: add missed unlock in raid_ctr

[dinghao.liu]

> > On Fri, Sep 3, 2021 at 10:02 AM Dinghao Liu dinghao.liu@zju.edu.cn> wrote:
> > mddev_unlock() is called on all paths after we call mddev_lock_nointr(),
> > except for three error handling paths, which may cause a deadlock. This
> > bug is suggested by a static analysis tool, please advise.
> > Hi,    
> >     
> >     correct, those unlock calls are missing.    
> >
> >     As we are bailing out after md_run() with lock held,     
> >     we can clean the lot of error paths underneath up by jumping to before
> >     md_stop() and add the mddev_unlock upfront it like:    
    
Thanks for your advice! I will fix this and send a new patch soon.

Regards,
Dinghao