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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Steffen Klassert <steffen.klassert@secunet.com>
Subject: [PATCH 4.4 38/72] xfrm: Refuse to insert 32 bit userspace socket policies on 64 bit systems
Date:   Fri,  6 Apr 2018 15:23:39 +0200
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Steffen Klassert <steffen.klassert@secunet.com>

commit 19d7df69fdb2636856dc8919de72fc1bf8f79598 upstream.

We don't have a compat layer for xfrm, so userspace and kernel
structures have different sizes in this case. This results in
a broken configuration, so refuse to configure socket policies
when trying to insert from 32 bit userspace as we do it already
with policies inserted via netlink.

Reported-and-tested-by: syzbot+e1a1577ca8bcb47b769a@syzkaller.appspotmail.com
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
[use is_compat_task() - gregkh]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/xfrm/xfrm_state.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -1845,6 +1845,11 @@ int xfrm_user_policy(struct sock *sk, in
 	struct xfrm_mgr *km;
 	struct xfrm_policy *pol = NULL;
 
+#ifdef CONFIG_COMPAT
+	if (is_compat_task())
+		return -EOPNOTSUPP;
+#endif
+
 	if (!optval && !optlen) {
 		xfrm_sk_policy_insert(sk, XFRM_POLICY_IN, NULL);
 		xfrm_sk_policy_insert(sk, XFRM_POLICY_OUT, NULL);