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https://github.com/Divested-Mobile/DivestOS-Build.git
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56 lines
1.9 KiB
Diff
56 lines
1.9 KiB
Diff
From 205e1e255c479f3fd77446415706463b282f94e4 Mon Sep 17 00:00:00 2001
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From: WANG Cong <xiyou.wangcong@gmail.com>
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Date: Tue, 5 Jul 2016 22:12:36 -0700
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Subject: ppp: defer netns reference release for ppp channel
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Matt reported that we have a NULL pointer dereference
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in ppp_pernet() from ppp_connect_channel(),
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i.e. pch->chan_net is NULL.
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This is due to that a parallel ppp_unregister_channel()
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could happen while we are in ppp_connect_channel(), during
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which pch->chan_net set to NULL. Since we need a reference
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to net per channel, it makes sense to sync the refcnt
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with the life time of the channel, therefore we should
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release this reference when we destroy it.
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Fixes: 1f461dcdd296 ("ppp: take reference on channels netns")
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Reported-by: Matt Bennett <Matt.Bennett@alliedtelesis.co.nz>
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Cc: Paul Mackerras <paulus@samba.org>
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Cc: linux-ppp@vger.kernel.org
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Cc: Guillaume Nault <g.nault@alphalink.fr>
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Cc: Cyrill Gorcunov <gorcunov@openvz.org>
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Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
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Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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drivers/net/ppp/ppp_generic.c | 5 +++--
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1 file changed, 3 insertions(+), 2 deletions(-)
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diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
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index 8dedafa..a30ee42 100644
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--- a/drivers/net/ppp/ppp_generic.c
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+++ b/drivers/net/ppp/ppp_generic.c
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@@ -2601,8 +2601,6 @@ ppp_unregister_channel(struct ppp_channel *chan)
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spin_lock_bh(&pn->all_channels_lock);
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list_del(&pch->list);
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spin_unlock_bh(&pn->all_channels_lock);
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- put_net(pch->chan_net);
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- pch->chan_net = NULL;
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pch->file.dead = 1;
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wake_up_interruptible(&pch->file.rwait);
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@@ -3136,6 +3134,9 @@ ppp_disconnect_channel(struct channel *pch)
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*/
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static void ppp_destroy_channel(struct channel *pch)
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{
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+ put_net(pch->chan_net);
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+ pch->chan_net = NULL;
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+
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atomic_dec(&channel_count);
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if (!pch->file.dead) {
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--
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cgit v1.1
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