From: Christian Brauner <brauner@kernel.org>
Date: Thu, 30 Mar 2023 09:13:16 +0200
Subject: [PATCH] fs: drop peer group ids under namespace lock
References: bsc#1012628
Patch-mainline: 6.2.11
Git-commit: cb2239c198ad9fbd5aced22cf93e45562da781eb

commit cb2239c198ad9fbd5aced22cf93e45562da781eb upstream.

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@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org # 5.12+
Message-Id: <20230330-vfs-mount_setattr-propagation-fix-v1-1-37548d91533b@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 fs/namespace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index ab467ee5..14fa31f1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -4286,9 +4286,9 @@ 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;
-- 
2.35.3