[Devel] [PATCH RH7 14/14] fs: drop peer group ids under namespace lock

[Pavel Tikhomirov]

From: Christian Brauner <brauner at kernel.org>

When cleaning up peer group ids in the failure path we need to make sure
to hold on to the namespace lock. Otherwise another thread might just
turn the mount from a shared into a non-shared mount concurrently.

Link: https://lore.kernel.org/lkml/00000000000088694505f8132d77@google.com
Fixes: 2a1867219c7b ("fs: add mount_setattr()")
Reported-by: syzbot+8ac3859139c685c4f597 at syzkaller.appspotmail.com
Cc: stable at vger.kernel.org # 5.12+
Message-Id: <20230330-vfs-mount_setattr-propagation-fix-v1-1-37548d91533b at kernel.org>
Signed-off-by: Christian Brauner <brauner at kernel.org>

(cherry picked from commit cb2239c198ad9fbd5aced22cf93e45562da781eb)
https://jira.sw.ru/browse/PSBM-144416
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 fs/namespace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index f37cae055dbf..49d972024249 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -4280,9 +4280,9 @@ static int do_mount_setattr(struct path *path, struct mount_kattr *kattr)
 	unlock_mount_hash();
 
 	if (kattr->propagation) {
-		namespace_unlock();
 		if (err)
 			cleanup_group_ids(mnt, NULL);
+		namespace_unlock();
 	}
 
 	return err;
-- 
2.39.2