From a3a1114aa6159b31319d44314737edcd0cff6932 Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel Date: Wed, 22 Sep 2021 10:50:06 +0200 Subject: [PATCH] xfrm: fix rcu lock in xfrm_notify_userpolicy() commit 93ec1320b0170d7a207eda2d119c669b673401ed upstream. As stated in the comment above xfrm_nlmsg_multicast(), rcu read lock must be held before calling this function. Reported-by: syzbot+3d9866419b4aa8f985d6@syzkaller.appspotmail.com Fixes: 703b94b93c19 ("xfrm: notify default policy on update") Signed-off-by: Nicolas Dichtel Signed-off-by: Steffen Klassert Signed-off-by: Greg Kroah-Hartman --- net/xfrm/xfrm_user.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index d9841f44487f..c6bf3898d1bf 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1920,6 +1920,7 @@ static int xfrm_notify_userpolicy(struct net *net) int len = NLMSG_ALIGN(sizeof(*up)); struct nlmsghdr *nlh; struct sk_buff *skb; + int err; skb = nlmsg_new(len, GFP_ATOMIC); if (skb == NULL) @@ -1938,7 +1939,11 @@ static int xfrm_notify_userpolicy(struct net *net) nlmsg_end(skb, nlh); - return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_POLICY); + rcu_read_lock(); + err = xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_POLICY); + rcu_read_unlock(); + + return err; } static bool xfrm_userpolicy_is_valid(__u8 policy)