On Thu, Nov 08, 2018 at 01:51:18PM -0800, Greg Kroah-Hartman wrote:
4.4-stable review patch. If anyone has any objections, please let me know.
This patch was partly wrong. Here is the followup fix: 94d7ee0baa8b ("l2tp: hold tunnel socket when handling control frames in l2tp_ip and l2tp_ip6")
Both a3c18422a4 ("l2tp: hold socket before dropping lock in l2tp_ip{, 6}_recv()") and 94d7ee0baa8b ("l2tp: hold tunnel socket when handling control frames in l2tp_ip and l2tp_ip6") should be applied/backported together.
[ Upstream commit a3c18422a4b4e108bcf6a2328f48867e1003fd95 ]
Socket must be held while under the protection of the l2tp lock; there is no guarantee that sk remains valid after the read_unlock_bh() call.
Same issue for l2tp_ip and l2tp_ip6.
Signed-off-by: Guillaume Nault g.nault@alphalink.fr Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org
net/l2tp/l2tp_ip.c | 11 ++++++----- net/l2tp/l2tp_ip6.c | 11 ++++++----- 2 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index 48ab93842322..c7e6098c924e 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -184,14 +184,15 @@ pass_up: read_lock_bh(&l2tp_ip_lock); sk = __l2tp_ip_bind_lookup(net, iph->daddr, 0, tunnel_id);
if (!sk) {read_unlock_bh(&l2tp_ip_lock);goto discard;}sock_hold(sk);
sock_hold(sk) is missing in the 'if' branch of this condition.
read_unlock_bh(&l2tp_ip_lock);}
- if (sk == NULL)
goto discard;- sock_hold(sk);
Original sock_hold(sk) covered both parts of the condition.
if (!xfrm4_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_put; diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c index bcdab1cba773..5fe0a6f6af3d 100644 --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -196,14 +196,15 @@ pass_up: read_lock_bh(&l2tp_ip6_lock); sk = __l2tp_ip6_bind_lookup(&init_net, &iph->daddr, 0, tunnel_id);
if (!sk) {read_unlock_bh(&l2tp_ip6_lock);goto discard;}sock_hold(sk);
Same here.
read_unlock_bh(&l2tp_ip6_lock);}
- if (sk == NULL)
goto discard;- sock_hold(sk);
- if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) goto discard_put;
2.17.1