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| author | Guillaume Nault <g.nault@alphalink.fr> | 2017-08-25 16:51:40 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-08-28 11:34:58 -0700 |
| commit | 54652eb12c1b72e9602d09cb2821d5760939190f (patch) | |
| tree | 3f53546dd44567d09e5070f0dbc8917902f6882e /net/l2tp/l2tp_netlink.c | |
| parent | 9ee369a405c57613d7c83a3967780c3e30c52ecc (diff) | |
| download | lwn-54652eb12c1b72e9602d09cb2821d5760939190f.tar.gz lwn-54652eb12c1b72e9602d09cb2821d5760939190f.zip | |
l2tp: hold tunnel while looking up sessions in l2tp_netlink
l2tp_tunnel_find() doesn't take a reference on the returned tunnel.
Therefore, it's unsafe to use it because the returned tunnel can go
away on us anytime.
Fix this by defining l2tp_tunnel_get(), which works like
l2tp_tunnel_find(), but takes a reference on the returned tunnel.
Caller then has to drop this reference using l2tp_tunnel_dec_refcount().
As l2tp_tunnel_dec_refcount() needs to be moved to l2tp_core.h, let's
simplify the patch and not move the L2TP_REFCNT_DEBUG part. This code
has been broken (not even compiling) in May 2012 by
commit a4ca44fa578c ("net: l2tp: Standardize logging styles")
and fixed more than two years later by
commit 29abe2fda54f ("l2tp: fix missing line continuation"). So it
doesn't appear to be used by anyone.
Same thing for l2tp_tunnel_free(); instead of moving it to l2tp_core.h,
let's just simplify things and call kfree_rcu() directly in
l2tp_tunnel_dec_refcount(). Extra assertions and debugging code
provided by l2tp_tunnel_free() didn't help catching any of the
reference counting and socket handling issues found while working on
this series.
Fixes: 309795f4bec2 ("l2tp: Add netlink control API for L2TP")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/l2tp/l2tp_netlink.c')
| -rw-r--r-- | net/l2tp/l2tp_netlink.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c index 12cfcd0ca807..27ee94b5c189 100644 --- a/net/l2tp/l2tp_netlink.c +++ b/net/l2tp/l2tp_netlink.c @@ -65,10 +65,12 @@ static struct l2tp_session *l2tp_nl_session_get(struct genl_info *info, (info->attrs[L2TP_ATTR_CONN_ID])) { tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]); session_id = nla_get_u32(info->attrs[L2TP_ATTR_SESSION_ID]); - tunnel = l2tp_tunnel_find(net, tunnel_id); - if (tunnel) + tunnel = l2tp_tunnel_get(net, tunnel_id); + if (tunnel) { session = l2tp_session_get(net, tunnel, session_id, do_ref); + l2tp_tunnel_dec_refcount(tunnel); + } } return session; |