From: Jiri Slaby <jslaby@suse.cz>
To: stable@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
WANG Cong <xiyou.wangcong@gmail.com>,
Paul Mackerras <paulus@samba.org>,
linux-ppp@vger.kernel.org, Guillaume Nault <g.nault@alphalink.fr>,
Cyrill Gorcunov <gorcunov@openvz.org>,
"David S . Miller" <davem@davemloft.net>,
Jiri Slaby <jslaby@suse.cz>
Subject: [PATCH 3.12 30/84] ppp: defer netns reference release for ppp channel
Date: Mon, 17 Oct 2016 07:51:17 +0000 [thread overview]
Message-ID: <e550951c8b8b1acb30e31c22ac3404648c9aa213.1476690493.git.jslaby@suse.cz> (raw)
In-Reply-To: <2d291fde5f706ac081e8cfc0ebe7e31dd534dfe7.1476690493.git.jslaby@suse.cz>
From: WANG Cong <xiyou.wangcong@gmail.com>
3.12-stable review patch. If anyone has any objections, please let me know.
=======
commit 205e1e255c479f3fd77446415706463b282f94e4 upstream.
Matt reported that we have a NULL pointer dereference
in ppp_pernet() from ppp_connect_channel(),
i.e. pch->chan_net is NULL.
This is due to that a parallel ppp_unregister_channel()
could happen while we are in ppp_connect_channel(), during
which pch->chan_net set to NULL. Since we need a reference
to net per channel, it makes sense to sync the refcnt
with the life time of the channel, therefore we should
release this reference when we destroy it.
Fixes: 1f461dcdd296 ("ppp: take reference on channels netns")
Reported-by: Matt Bennett <Matt.Bennett@alliedtelesis.co.nz>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linux-ppp@vger.kernel.org
Cc: Guillaume Nault <g.nault@alphalink.fr>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/net/ppp/ppp_generic.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 14a8d2958698..ab79c0f13d0a 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -2317,8 +2317,6 @@ ppp_unregister_channel(struct ppp_channel *chan)
spin_lock_bh(&pn->all_channels_lock);
list_del(&pch->list);
spin_unlock_bh(&pn->all_channels_lock);
- put_net(pch->chan_net);
- pch->chan_net = NULL;
pch->file.dead = 1;
wake_up_interruptible(&pch->file.rwait);
@@ -2925,6 +2923,9 @@ ppp_disconnect_channel(struct channel *pch)
*/
static void ppp_destroy_channel(struct channel *pch)
{
+ put_net(pch->chan_net);
+ pch->chan_net = NULL;
+
atomic_dec(&channel_count);
if (!pch->file.dead) {
--
2.10.1
parent reply other threads:[~2016-10-17 7:51 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <2d291fde5f706ac081e8cfc0ebe7e31dd534dfe7.1476690493.git.jslaby@suse.cz>]
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