[for-3.18,04/15] ppp: take reference on channels netns

Message ID 1501015526-32178-5-git-send-email-amit.pundir@linaro.org
State New
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Series
  • Stable candidates for 3.18.y
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Commit Message

Amit Pundir July 25, 2017, 8:45 p.m.
From: Guillaume Nault <g.nault@alphalink.fr>


commit 1f461dcdd296eecedaffffc6bae2bfa90bd7eb89 upstream.

Let channels hold a reference on their network namespace.
Some channel types, like ppp_async and ppp_synctty, can have their
userspace controller running in a different namespace. Therefore they
can't rely on them to preclude their netns from being removed from
under them.

-- 
2.7.4

Comments

Guillaume Nault July 26, 2017, 9:52 a.m. | #1
On Wed, Jul 26, 2017 at 02:15:15AM +0530, Amit Pundir wrote:
> From: Guillaume Nault <g.nault@alphalink.fr>

> 

> commit 1f461dcdd296eecedaffffc6bae2bfa90bd7eb89 upstream.

> 

> Let channels hold a reference on their network namespace.

> Some channel types, like ppp_async and ppp_synctty, can have their

> userspace controller running in a different namespace. Therefore they

> can't rely on them to preclude their netns from being removed from

> under them.

> 

Hi Amit,

I don't know how you got there, but one chunk is missing in your
backport (same problem happened in your -4.4 series):
@@ -2307,7 +2307,7 @@ int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)
 
        pch->ppp = NULL;
        pch->chan = chan;
-       pch->chan_net = net;
+       pch->chan_net = get_net(net);
        chan->ppp = pch;
        init_ppp_file(&pch->file, CHANNEL);
        pch->file.hdrlen = chan->hdrlen;

Also, any backport of commit 1f461dcdd296 ("ppp: take reference on channels netns")
should be accompanied by commit 205e1e255c47 ("ppp: defer netns reference release for ppp channel").

Anyway, both are already present in stable/linux-3.18.y, so this patch
can be dropped from your series.
And FWIW, I think linux-3.18.y isn't maintained anymore.

> 

> Fixes: 273ec51dd7ce ("net: ppp_generic - introduce net-namespace functionality v2")

> Reported-by: Baozeng Ding <sploving1@gmail.com>

> Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>

> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>

> Signed-off-by: David S. Miller <davem@davemloft.net>

> Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

> ---

>  drivers/net/ppp/ppp_generic.c | 2 ++

>  1 file changed, 2 insertions(+)

> 

> diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c

> index 3dd1c19756ec..38c0231fb9b7 100644

> --- a/drivers/net/ppp/ppp_generic.c

> +++ b/drivers/net/ppp/ppp_generic.c

> @@ -2342,6 +2342,8 @@ 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);

> -- 

> 2.7.4

>
Amit Pundir July 26, 2017, 10:30 a.m. | #2
On 26 July 2017 at 15:22, Guillaume Nault <g.nault@alphalink.fr> wrote:
> On Wed, Jul 26, 2017 at 02:15:15AM +0530, Amit Pundir wrote:

>> From: Guillaume Nault <g.nault@alphalink.fr>

>>

>> commit 1f461dcdd296eecedaffffc6bae2bfa90bd7eb89 upstream.

>>

>> Let channels hold a reference on their network namespace.

>> Some channel types, like ppp_async and ppp_synctty, can have their

>> userspace controller running in a different namespace. Therefore they

>> can't rely on them to preclude their netns from being removed from

>> under them.

>>

> Hi Amit,

>

> I don't know how you got there, but one chunk is missing in your

> backport (same problem happened in your -4.4 series):

> @@ -2307,7 +2307,7 @@ int ppp_register_net_channel(struct net *net, struct ppp_channel *chan)

>

>         pch->ppp = NULL;

>         pch->chan = chan;

> -       pch->chan_net = net;

> +       pch->chan_net = get_net(net);

>         chan->ppp = pch;

>         init_ppp_file(&pch->file, CHANNEL);

>         pch->file.hdrlen = chan->hdrlen;

>

> Also, any backport of commit 1f461dcdd296 ("ppp: take reference on channels netns")

> should be accompanied by commit 205e1e255c47 ("ppp: defer netns reference release for ppp channel").

>

> Anyway, both are already present in stable/linux-3.18.y, so this patch

> can be dropped from your series.


Thanks Guillaume. I realised that too earlier today. Somehow "git
cherry-pick" didn't complain this time. I replied on 4.4 series to
ignore this patch but forgot to do that on this 3.18 patch. Thanks for
pointing it out.

> And FWIW, I think linux-3.18.y isn't maintained anymore.


linux-3.18.y is still getting maintained. See
https://lkml.org/lkml/2017/4/16/209.

Regards,
Amit Pundir

>

>>

>> Fixes: 273ec51dd7ce ("net: ppp_generic - introduce net-namespace functionality v2")

>> Reported-by: Baozeng Ding <sploving1@gmail.com>

>> Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>

>> Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>

>> Signed-off-by: David S. Miller <davem@davemloft.net>

>> Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

>> ---

>>  drivers/net/ppp/ppp_generic.c | 2 ++

>>  1 file changed, 2 insertions(+)

>>

>> diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c

>> index 3dd1c19756ec..38c0231fb9b7 100644

>> --- a/drivers/net/ppp/ppp_generic.c

>> +++ b/drivers/net/ppp/ppp_generic.c

>> @@ -2342,6 +2342,8 @@ 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);

>> --

>> 2.7.4

>>

Patch

==================================================================
BUG: KASAN: use-after-free in ppp_unregister_channel+0x372/0x3a0 at
addr ffff880064e217e0
Read of size 8 by task syz-executor/11581
=============================================================================
BUG net_namespace (Not tainted): kasan: bad access detected
-----------------------------------------------------------------------------

Disabling lock debugging due to kernel taint
INFO: Allocated in copy_net_ns+0x6b/0x1a0 age=92569 cpu=3 pid=6906
[<      none      >] ___slab_alloc+0x4c7/0x500 kernel/mm/slub.c:2440
[<      none      >] __slab_alloc+0x4c/0x90 kernel/mm/slub.c:2469
[<     inline     >] slab_alloc_node kernel/mm/slub.c:2532
[<     inline     >] slab_alloc kernel/mm/slub.c:2574
[<      none      >] kmem_cache_alloc+0x23a/0x2b0 kernel/mm/slub.c:2579
[<     inline     >] kmem_cache_zalloc kernel/include/linux/slab.h:597
[<     inline     >] net_alloc kernel/net/core/net_namespace.c:325
[<      none      >] copy_net_ns+0x6b/0x1a0 kernel/net/core/net_namespace.c:360
[<      none      >] create_new_namespaces+0x2f6/0x610 kernel/kernel/nsproxy.c:95
[<      none      >] copy_namespaces+0x297/0x320 kernel/kernel/nsproxy.c:150
[<      none      >] copy_process.part.35+0x1bf4/0x5760 kernel/kernel/fork.c:1451
[<     inline     >] copy_process kernel/kernel/fork.c:1274
[<      none      >] _do_fork+0x1bc/0xcb0 kernel/kernel/fork.c:1723
[<     inline     >] SYSC_clone kernel/kernel/fork.c:1832
[<      none      >] SyS_clone+0x37/0x50 kernel/kernel/fork.c:1826
[<      none      >] entry_SYSCALL_64_fastpath+0x16/0x7a kernel/arch/x86/entry/entry_64.S:185

INFO: Freed in net_drop_ns+0x67/0x80 age=575 cpu=2 pid=2631
[<      none      >] __slab_free+0x1fc/0x320 kernel/mm/slub.c:2650
[<     inline     >] slab_free kernel/mm/slub.c:2805
[<      none      >] kmem_cache_free+0x2a0/0x330 kernel/mm/slub.c:2814
[<     inline     >] net_free kernel/net/core/net_namespace.c:341
[<      none      >] net_drop_ns+0x67/0x80 kernel/net/core/net_namespace.c:348
[<      none      >] cleanup_net+0x4e5/0x600 kernel/net/core/net_namespace.c:448
[<      none      >] process_one_work+0x794/0x1440 kernel/kernel/workqueue.c:2036
[<      none      >] worker_thread+0xdb/0xfc0 kernel/kernel/workqueue.c:2170
[<      none      >] kthread+0x23f/0x2d0 kernel/drivers/block/aoe/aoecmd.c:1303
[<      none      >] ret_from_fork+0x3f/0x70 kernel/arch/x86/entry/entry_64.S:468
INFO: Slab 0xffffea0001938800 objects=3 used=0 fp=0xffff880064e20000
flags=0x5fffc0000004080
INFO: Object 0xffff880064e20000 @offset=0 fp=0xffff880064e24200

CPU: 1 PID: 11581 Comm: syz-executor Tainted: G    B           4.4.0+
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
 00000000ffffffff ffff8800662c7790 ffffffff8292049d ffff88003e36a300
 ffff880064e20000 ffff880064e20000 ffff8800662c77c0 ffffffff816f2054
 ffff88003e36a300 ffffea0001938800 ffff880064e20000 0000000000000000
Call Trace:
 [<     inline     >] __dump_stack kernel/lib/dump_stack.c:15
 [<ffffffff8292049d>] dump_stack+0x6f/0xa2 kernel/lib/dump_stack.c:50
 [<ffffffff816f2054>] print_trailer+0xf4/0x150 kernel/mm/slub.c:654
 [<ffffffff816f875f>] object_err+0x2f/0x40 kernel/mm/slub.c:661
 [<     inline     >] print_address_description kernel/mm/kasan/report.c:138
 [<ffffffff816fb0c5>] kasan_report_error+0x215/0x530 kernel/mm/kasan/report.c:236
 [<     inline     >] kasan_report kernel/mm/kasan/report.c:259
 [<ffffffff816fb4de>] __asan_report_load8_noabort+0x3e/0x40 kernel/mm/kasan/report.c:280
 [<     inline     >] ? ppp_pernet kernel/include/linux/compiler.h:218
 [<ffffffff83ad71b2>] ? ppp_unregister_channel+0x372/0x3a0 kernel/drivers/net/ppp/ppp_generic.c:2392
 [<     inline     >] ppp_pernet kernel/include/linux/compiler.h:218
 [<ffffffff83ad71b2>] ppp_unregister_channel+0x372/0x3a0 kernel/drivers/net/ppp/ppp_generic.c:2392
 [<     inline     >] ? ppp_pernet kernel/drivers/net/ppp/ppp_generic.c:293
 [<ffffffff83ad6f26>] ? ppp_unregister_channel+0xe6/0x3a0 kernel/drivers/net/ppp/ppp_generic.c:2392
 [<ffffffff83ae18f3>] ppp_asynctty_close+0xa3/0x130 kernel/drivers/net/ppp/ppp_async.c:241
 [<ffffffff83ae1850>] ? async_lcp_peek+0x5b0/0x5b0 kernel/drivers/net/ppp/ppp_async.c:1000
 [<ffffffff82c33239>] tty_ldisc_close.isra.1+0x99/0xe0 kernel/drivers/tty/tty_ldisc.c:478
 [<ffffffff82c332c0>] tty_ldisc_kill+0x40/0x170 kernel/drivers/tty/tty_ldisc.c:744
 [<ffffffff82c34943>] tty_ldisc_release+0x1b3/0x260 kernel/drivers/tty/tty_ldisc.c:772
 [<ffffffff82c1ef21>] tty_release+0xac1/0x13e0 kernel/drivers/tty/tty_io.c:1901
 [<ffffffff82c1e460>] ? release_tty+0x320/0x320 kernel/drivers/tty/tty_io.c:1688
 [<ffffffff8174de36>] __fput+0x236/0x780 kernel/fs/file_table.c:208
 [<ffffffff8174e405>] ____fput+0x15/0x20 kernel/fs/file_table.c:244
 [<ffffffff813595ab>] task_work_run+0x16b/0x200 kernel/kernel/task_work.c:115
 [<     inline     >] exit_task_work kernel/include/linux/task_work.h:21
 [<ffffffff81307105>] do_exit+0x8b5/0x2c60 kernel/kernel/exit.c:750
 [<ffffffff813fdd20>] ? debug_check_no_locks_freed+0x290/0x290 kernel/kernel/locking/lockdep.c:4123
 [<ffffffff81306850>] ? mm_update_next_owner+0x6f0/0x6f0 kernel/kernel/exit.c:357
 [<ffffffff813215e6>] ? __dequeue_signal+0x136/0x470 kernel/kernel/signal.c:550
 [<ffffffff8132067b>] ? recalc_sigpending_tsk+0x13b/0x180 kernel/kernel/signal.c:145
 [<ffffffff81309628>] do_group_exit+0x108/0x330 kernel/kernel/exit.c:880
 [<ffffffff8132b9d4>] get_signal+0x5e4/0x14f0 kernel/kernel/signal.c:2307
 [<     inline     >] ? kretprobe_table_lock kernel/kernel/kprobes.c:1113
 [<ffffffff8151d355>] ? kprobe_flush_task+0xb5/0x450 kernel/kernel/kprobes.c:1158
 [<ffffffff8115f7d3>] do_signal+0x83/0x1c90 kernel/arch/x86/kernel/signal.c:712
 [<ffffffff8151d2a0>] ? recycle_rp_inst+0x310/0x310 kernel/include/linux/list.h:655
 [<ffffffff8115f750>] ? setup_sigcontext+0x780/0x780 kernel/arch/x86/kernel/signal.c:165
 [<ffffffff81380864>] ? finish_task_switch+0x424/0x5f0 kernel/kernel/sched/core.c:2692
 [<     inline     >] ? finish_lock_switch kernel/kernel/sched/sched.h:1099
 [<ffffffff81380560>] ? finish_task_switch+0x120/0x5f0 kernel/kernel/sched/core.c:2678
 [<     inline     >] ? context_switch kernel/kernel/sched/core.c:2807
 [<ffffffff85d794e9>] ? __schedule+0x919/0x1bd0 kernel/kernel/sched/core.c:3283
 [<ffffffff81003901>] exit_to_usermode_loop+0xf1/0x1a0 kernel/arch/x86/entry/common.c:247
 [<     inline     >] prepare_exit_to_usermode kernel/arch/x86/entry/common.c:282
 [<ffffffff810062ef>] syscall_return_slowpath+0x19f/0x210 kernel/arch/x86/entry/common.c:344
 [<ffffffff85d88022>] int_ret_from_sys_call+0x25/0x9f kernel/arch/x86/entry/entry_64.S:281
Memory state around the buggy address:
 ffff880064e21680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880064e21700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff880064e21780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff880064e21800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff880064e21880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fixes: 273ec51dd7ce ("net: ppp_generic - introduce net-namespace functionality v2")
Reported-by: Baozeng Ding <sploving1@gmail.com>
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
---
 drivers/net/ppp/ppp_generic.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 3dd1c19756ec..38c0231fb9b7 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -2342,6 +2342,8 @@  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);