From: Nicolas Dichtel nicolas.dichtel@6wind.com

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: 9856c3a129dd ("xfrm: notify default policy on update") Signed-off-by: Nicolas Dichtel nicolas.dichtel@6wind.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Fedor Pchelkin pchelkin@ispras.ru --- net/xfrm/xfrm_user.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index d9841f44487f..b5a517916895 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 +1939,10 @@ 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)