UPSTREAM: ppp: defer netns reference release for ppp channel

(cherry pick from commit 205e1e255c479f3fd77446415706463b282f94e4)

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 <>
Cc: Paul Mackerras <>
Cc: Guillaume Nault <>
Cc: Cyrill Gorcunov <>
Signed-off-by: Cong Wang <>
Reviewed-by: Cyrill Gorcunov <>
Signed-off-by: David S. Miller <>

Fixes: Change-Id: Iee0015eca5bd181954bb4896a3720f7549c5ed0b ("UPSTREAM:
ppp: take reference on channels netns")
Signed-off-by: Amit Pundir <>
Change-Id: I24d0bb6f349ab3829f63cfe935ed97b6913a3508
1 file changed