Don't leak MNT_INTERNAL away from internal mounts

commit 16a34adb9392b2fe4195267475ab5b472e55292c upstream.

We want it only for the stuff created by SB_KERNMOUNT mounts, *not* for
their copies.  As it is, creating a deep stack of bindings of /proc/*/ns/*
somewhere in a new namespace and exiting yields a stack overflow.

Cc: stable@kernel.org
Reported-by: Alexander Aring <aring@mojatatu.com>
Bisected-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/namespace.c b/fs/namespace.c
index d7360f9897b4b3a3814effb37c1bc089f81d8b72..6c873b330a936ca664f8718a25c9a590a3089b7a 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1033,7 +1033,8 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
                        goto out_free;
        }
 
-       mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED);
+       mnt->mnt.mnt_flags = old->mnt.mnt_flags;
+       mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL);
        /* Don't allow unprivileged users to change mount flags */
        if (flag & CL_UNPRIVILEGED) {
                mnt->mnt.mnt_flags |= MNT_LOCK_ATIME;