From 12f147ddd6de7382dad54812e65f3f08d05809fc Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 4 Jun 2025 12:27:08 -0400 Subject: [PATCH] do_change_type(): refuse to operate on unmounted/not ours mounts Ensure that propagation settings can only be changed for mounts located in the caller's mount namespace. This change aligns permission checking with the rest of mount(2). Reviewed-by: Christian Brauner Fixes: 07b20889e305 ("beginning of the shared-subtree proper") Reported-by: "Orlando, Noah" Signed-off-by: Al Viro --- fs/namespace.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index 1c54c16c7bab..2721d64ecfdf 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2959,6 +2959,10 @@ static int do_change_type(struct path *path, int ms_flags) return -EINVAL; namespace_lock(); + if (!check_mnt(mnt)) { + err = -EINVAL; + goto out_unlock; + } if (type == MS_SHARED) { err = invent_group_ids(mnt, recurse); if (err) -- 2.25.1