From: Christian Brauner <brauner@xxxxxxxxxx> 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@xxxxxxxxxx Fixes: 2a1867219c7b ("fs: add mount_setattr()") Reported-by: syzbot+8ac3859139c685c4f597@xxxxxxxxxxxxxxxxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx # 5.12+ Message-Id: <20230330-vfs-mount_setattr-propagation-fix-v1-1-37548d91533b@xxxxxxxxxx> Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4121,9 +4121,9 @@ static int do_mount_setattr(struct path unlock_mount_hash(); if (kattr->propagation) { - namespace_unlock(); if (err) cleanup_group_ids(mnt, NULL); + namespace_unlock(); } return err;
