From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 20 Apr 2018 02:03:08 +0000 (-0400)
Subject: Don't leak MNT_INTERNAL away from internal mounts
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=3f68e22e9bd1f06a0b752c742bfab530fcd8bd74;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

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 d7360f9897b4..6c873b330a93 100644
--- 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;