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authorTom Parkin <tparkin@katalix.com>2020-09-03 09:54:51 +0100
committerDavid S. Miller <davem@davemloft.net>2020-09-03 12:19:03 -0700
commit45faeff11b48b9390ee946668119472b8941de90 (patch)
tree34531885982004902029c4b5d81bd3fc185d0a1f /net/l2tp/l2tp_ip6.c
parentde68b039e970c1e55850818fb1bcd49f52dc02e8 (diff)
l2tp: make magic feather checks more useful
The l2tp tunnel and session structures contain a "magic feather" field which was originally intended to help trace lifetime bugs in the code. Since the introduction of the shared kernel refcount code in refcount.h, and l2tp's porting to those APIs, we are covered by the refcount code's checks and warnings. Duplicating those checks in the l2tp code isn't useful. However, magic feather checks are still useful to help to detect bugs stemming from misuse/trampling of the sk_user_data pointer in struct sock. The l2tp code makes extensive use of sk_user_data to stash pointers to the tunnel and session structures, and if another subsystem overwrites sk_user_data it's important to detect this. As such, rework l2tp's magic feather checks to focus on validating the tunnel and session data structures when they're extracted from sk_user_data. * Add a new accessor function l2tp_sk_to_tunnel which contains a magic feather check, and is used by l2tp_core and l2tp_ip[6] * Comment l2tp_udp_encap_recv which doesn't use this new accessor function because of the specific nature of the codepath it is called in * Drop l2tp_session_queue_purge's check on the session magic feather: it is called from code which is walking the tunnel session list, and hence doesn't need validation * Drop l2tp_session_free's check on the tunnel magic feather: the intention of this check is covered by refcount.h's reference count sanity checking * Add session magic validation in pppol2tp_ioctl. On failure return -EBADF, which mirrors the approach in pppol2tp_[sg]etsockopt. Signed-off-by: Tom Parkin <tparkin@katalix.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/l2tp/l2tp_ip6.c')
-rw-r--r--net/l2tp/l2tp_ip6.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index 409ea8927f6c..e5e5036257b0 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -247,7 +247,7 @@ static void l2tp_ip6_close(struct sock *sk, long timeout)
static void l2tp_ip6_destroy_sock(struct sock *sk)
{
- struct l2tp_tunnel *tunnel = sk->sk_user_data;
+ struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk);
lock_sock(sk);
ip6_flush_pending_frames(sk);