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| author | WANG Cong <xiyou.wangcong@gmail.com> | 2016-07-06 07:12:36 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-07-09 05:46:37 +0200 |
| commit | 205e1e255c479f3fd77446415706463b282f94e4 (patch) | |
| tree | 98e80b94c077894fb29591ba610da272349549cd /drivers/net/ppp/ppp_generic.c | |
| parent | net: mvneta: set real interrupt per packet for tx_done (diff) | |
| download | linux-205e1e255c479f3fd77446415706463b282f94e4.tar.xz linux-205e1e255c479f3fd77446415706463b282f94e4.zip | |
ppp: defer netns reference release for ppp channel
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>
Diffstat (limited to 'drivers/net/ppp/ppp_generic.c')
| -rw-r--r-- | drivers/net/ppp/ppp_generic.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c index 8dedafa1a95d..a30ee427efab 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -2601,8 +2601,6 @@ 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); @@ -3136,6 +3134,9 @@ 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) { |