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Eric W. Biederman b9f75f45a6 netns: Don't receive new packets in a dead network namespace. 
Alexey Dobriyan <adobriyan@gmail.com> writes:
> Subject: ICMP sockets destruction vs ICMP packets oops

> After icmp_sk_exit() nuked ICMP sockets, we get an interrupt.
> icmp_reply() wants ICMP socket.
>
> Steps to reproduce:
>
> 	launch shell in new netns
> 	move real NIC to netns
> 	setup routing
> 	ping -i 0
> 	exit from shell
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
> IP: [<ffffffff803fce17>] icmp_sk+0x17/0x30
> PGD 17f3cd067 PUD 17f3ce067 PMD 0 
> Oops: 0000 [1] PREEMPT SMP DEBUG_PAGEALLOC
> CPU 0 
> Modules linked in: usblp usbcore
> Pid: 0, comm: swapper Not tainted 2.6.26-rc6-netns-ct #4
> RIP: 0010:[<ffffffff803fce17>]  [<ffffffff803fce17>] icmp_sk+0x17/0x30
> RSP: 0018:ffffffff8057fc30  EFLAGS: 00010286
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff81017c7db900
> RDX: 0000000000000034 RSI: ffff81017c7db900 RDI: ffff81017dc41800
> RBP: ffffffff8057fc40 R08: 0000000000000001 R09: 000000000000a815
> R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff8057fd28
> R13: ffffffff8057fd00 R14: ffff81017c7db938 R15: ffff81017dc41800
> FS:  0000000000000000(0000) GS:ffffffff80525000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
> CR2: 0000000000000000 CR3: 000000017fcda000 CR4: 00000000000006e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process swapper (pid: 0, threadinfo ffffffff8053a000, task ffffffff804fa4a0)
> Stack:  0000000000000000 ffff81017c7db900 ffffffff8057fcf0 ffffffff803fcfe4
>  ffffffff804faa38 0000000000000246 0000000000005a40 0000000000000246
>  000000000001ffff ffff81017dd68dc0 0000000000005a40 0000000055342436
> Call Trace:
>  <IRQ>  [<ffffffff803fcfe4>] icmp_reply+0x44/0x1e0
>  [<ffffffff803d3a0a>] ? ip_route_input+0x23a/0x1360
>  [<ffffffff803fd645>] icmp_echo+0x65/0x70
>  [<ffffffff803fd300>] icmp_rcv+0x180/0x1b0
>  [<ffffffff803d6d84>] ip_local_deliver+0xf4/0x1f0
>  [<ffffffff803d71bb>] ip_rcv+0x33b/0x650
>  [<ffffffff803bb16a>] netif_receive_skb+0x27a/0x340
>  [<ffffffff803be57d>] process_backlog+0x9d/0x100
>  [<ffffffff803bdd4d>] net_rx_action+0x18d/0x250
>  [<ffffffff80237be5>] __do_softirq+0x75/0x100
>  [<ffffffff8020c97c>] call_softirq+0x1c/0x30
>  [<ffffffff8020f085>] do_softirq+0x65/0xa0
>  [<ffffffff80237af7>] irq_exit+0x97/0xa0
>  [<ffffffff8020f198>] do_IRQ+0xa8/0x130
>  [<ffffffff80212ee0>] ? mwait_idle+0x0/0x60
>  [<ffffffff8020bc46>] ret_from_intr+0x0/0xf
>  <EOI>  [<ffffffff80212f2c>] ? mwait_idle+0x4c/0x60
>  [<ffffffff80212f23>] ? mwait_idle+0x43/0x60
>  [<ffffffff8020a217>] ? cpu_idle+0x57/0xa0
>  [<ffffffff8040f380>] ? rest_init+0x70/0x80
> Code: 10 5b 41 5c 41 5d 41 5e c9 c3 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 53
> 48 83 ec 08 48 8b 9f 78 01 00 00 e8 2b c7 f1 ff 89 c0 <48> 8b 04 c3 48 83 c4 08
> 5b c9 c3 66 66 66 66 66 2e 0f 1f 84 00
> RIP  [<ffffffff803fce17>] icmp_sk+0x17/0x30
>  RSP <ffffffff8057fc30>
> CR2: 0000000000000000
> ---[ end trace ea161157b76b33e8 ]---
> Kernel panic - not syncing: Aiee, killing interrupt handler!

Receiving packets while we are cleaning up a network namespace is a
racy proposition. It is possible when the packet arrives that we have
removed some but not all of the state we need to fully process it.  We
have the choice of either playing wack-a-mole with the cleanup routines
or simply dropping packets when we don't have a network namespace to
handle them.

Since the check looks inexpensive in netif_receive_skb let's just
drop the incoming packets.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-06-20 22:16:51 -07:00
..
datagram.c [NET] CORE: Introducing new memory accounting interface. 2008-01-28 15:00:18 -08:00
dev.c netns: Don't receive new packets in a dead network namespace. 2008-06-20 22:16:51 -07:00
dev_mcast.c [NET]: Use existing device list walker for /proc/dev_mcast. 2008-02-29 11:44:14 -08:00
dst.c [NET]: uninline dst_release 2008-03-27 17:53:31 -07:00
ethtool.c ethtool: EEPROM dump no longer works for tg3 and natsemi 2008-04-24 20:55:56 -07:00
fib_rules.c [NETNS]: Add netns refcnt debug to fib rules. 2008-04-16 02:01:56 -07:00
filter.c net: use get/put_unaligned_* helpers 2008-05-02 16:26:16 -07:00
flow.c net: Remove unnecessary inclusions of asm/semaphore.h 2008-04-18 22:15:50 -04:00
gen_estimator.c [NET_SCHED]: Convert packet schedulers from rtnetlink to new netlink API 2008-01-28 15:11:10 -08:00
gen_stats.c [NET_SCHED]: Convert packet schedulers from rtnetlink to new netlink API 2008-01-28 15:11:10 -08:00
iovec.c [PATCH] remove many unneeded #includes of sched.h 2007-02-14 08:09:54 -08:00
kmap_skb.h [PATCH] severing skbuff.h -> highmem.h 2006-12-04 02:00:29 -05:00
link_watch.c [NET] link_watch: Always schedule urgent events 2007-05-10 23:45:28 -07:00
Makefile [NET]: Fix running without sysfs 2007-10-10 16:52:46 -07:00
neighbour.c netlink: Improve returned error codes 2008-06-03 16:36:54 -07:00
net-sysfs.c netns: Fix device renaming for sysfs 2008-05-02 17:00:58 -07:00
net-sysfs.h netns: Fix device renaming for sysfs 2008-05-02 17:00:58 -07:00
net_namespace.c netns: Don't receive new packets in a dead network namespace. 2008-06-20 22:16:51 -07:00
netevent.c [NET]: net/core/netevent.c should #include <net/netevent.h> 2007-07-05 17:40:27 -07:00
netpoll.c net: Allow netdevices to specify needed head/tailroom 2008-05-12 20:48:31 -07:00
pktgen.c pktgen: make sure that pktgen_thread_worker has been executed 2008-05-20 15:12:44 -07:00
request_sock.c [NET] net/core/request_sock.c: Remove unused exports. 2008-01-28 14:54:33 -08:00
rtnetlink.c netlink: Improve returned error codes 2008-06-03 16:36:54 -07:00
scm.c [NET]: Fix function put_cmsg() which may cause usr application memory overflow 2007-12-20 14:36:44 -08:00
skbuff.c tcp: Fix for race due to temporary drop of the socket lock in skb_splice_bits. 2008-06-04 15:45:58 -07:00
sock.c net: Fix typo in net/core/sock.c. 2008-05-14 03:50:03 -07:00
stream.c [NET] CORE: Introducing new memory accounting interface. 2008-01-28 15:00:18 -08:00
sysctl_net_core.c [NETNS]: Introduce a netns_core structure. 2008-03-31 19:41:14 -07:00
user_dma.c net_dma: remove duplicate assignment in dma_skb_copy_datagram_iovec 2008-06-03 16:07:45 -07:00
utils.c [NET] core/utils.c: digit2bin is dead static inline 2008-01-28 15:01:58 -08:00