linux-stable.git/include/net, branch v3.16.73 Linux kernel stable tree tcp: Clear sk_send_head after purging the write queue 2019-08-20T18:01:55+00:00 Ben Hutchings ben@decadent.org.uk 2019-08-03T16:11:42+00:00 3157fbc900bdb366b2186e5a6e506cc5e4697cf0 Denis Andzakovic discovered a potential use-after-free in older kernel versions, using syzkaller. tcp_write_queue_purge() frees all skbs in the TCP write queue and can leave sk->sk_send_head pointing to freed memory. tcp_disconnect() clears that pointer after calling tcp_write_queue_purge(), but tcp_connect() does not. It is (surprisingly) possible to add to the write queue between disconnection and reconnection, so this needs to be done in both places. This bug was introduced by backports of commit 7f582b248d0a ("tcp: purge write queue in tcp_connect_init()") and does not exist upstream because of earlier changes in commit 75c119afe14f ("tcp: implement rb-tree based retransmit queue"). The latter is a major change that's not suitable for stable. Reported-by: Denis Andzakovic <denis.andzakovic@pulsesecurity.co.nz> Bisected-by: Salvatore Bonaccorso <carnil@debian.org> Fixes: 7f582b248d0a ("tcp: purge write queue in tcp_connect_init()") Cc: <stable@vger.kernel.org> # before 4.15 Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
Denis Andzakovic discovered a potential use-after-free in older kernel
versions, using syzkaller.  tcp_write_queue_purge() frees all skbs in
the TCP write queue and can leave sk->sk_send_head pointing to freed
memory.  tcp_disconnect() clears that pointer after calling
tcp_write_queue_purge(), but tcp_connect() does not.  It is
(surprisingly) possible to add to the write queue between
disconnection and reconnection, so this needs to be done in both
places.

This bug was introduced by backports of commit 7f582b248d0a ("tcp:
purge write queue in tcp_connect_init()") and does not exist upstream
because of earlier changes in commit 75c119afe14f ("tcp: implement
rb-tree based retransmit queue").  The latter is a major change that's
not suitable for stable.

Reported-by: Denis Andzakovic <denis.andzakovic@pulsesecurity.co.nz>
Bisected-by: Salvatore Bonaccorso <carnil@debian.org>
Fixes: 7f582b248d0a ("tcp: purge write queue in tcp_connect_init()")
Cc: <stable@vger.kernel.org> # before 4.15
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
netfilter: ctnetlink: don't use conntrack/expect object addresses as id 2019-08-13T11:39:32+00:00 Florian Westphal fw@strlen.de 2019-04-01T11:08:54+00:00 3d8b3d0384f709126beef6b917b7e97c23f18e74 commit 3c79107631db1f7fd32cf3f7368e4672004a3010 upstream. else, we leak the addresses to userspace via ctnetlink events and dumps. Compute an ID on demand based on the immutable parts of nf_conn struct. Another advantage compared to using an address is that there is no immediate re-use of the same ID in case the conntrack entry is freed and reallocated again immediately. Fixes: 3583240249ef ("[NETFILTER]: nf_conntrack_expect: kill unique ID") Fixes: 7f85f914721f ("[NETFILTER]: nf_conntrack: kill unique ID") Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> [bwh: Backported to 3.16: - Include <net/netns/hash.h> in nf_conntrack_core.c - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 3c79107631db1f7fd32cf3f7368e4672004a3010 upstream.

else, we leak the addresses to userspace via ctnetlink events
and dumps.

Compute an ID on demand based on the immutable parts of nf_conn struct.

Another advantage compared to using an address is that there is no
immediate re-use of the same ID in case the conntrack entry is freed and
reallocated again immediately.

Fixes: 3583240249ef ("[NETFILTER]: nf_conntrack_expect: kill unique ID")
Fixes: 7f85f914721f ("[NETFILTER]: nf_conntrack: kill unique ID")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[bwh: Backported to 3.16:
 - Include <net/netns/hash.h> in nf_conntrack_core.c
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
inet: switch IP ID generator to siphash 2019-08-13T11:39:32+00:00 Eric Dumazet edumazet@google.com 2019-03-27T19:40:33+00:00 9ebeec41ed3f52fd94267f25f8b9bf3f4cbf1e4e commit df453700e8d81b1bdafdf684365ee2b9431fb702 upstream. According to Amit Klein and Benny Pinkas, IP ID generation is too weak and might be used by attackers. Even with recent net_hash_mix() fix (netns: provide pure entropy for net_hash_mix()) having 64bit key and Jenkins hash is risky. It is time to switch to siphash and its 128bit keys. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Amit Klein <aksecurity@gmail.com> Reported-by: Benny Pinkas <benny@pinkas.net> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit df453700e8d81b1bdafdf684365ee2b9431fb702 upstream.

According to Amit Klein and Benny Pinkas, IP ID generation is too weak
and might be used by attackers.

Even with recent net_hash_mix() fix (netns: provide pure entropy for net_hash_mix())
having 64bit key and Jenkins hash is risky.

It is time to switch to siphash and its 128bit keys.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Amit Klein <aksecurity@gmail.com>
Reported-by: Benny Pinkas <benny@pinkas.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ipv6: hash net ptr into fragmentation bucket selection 2019-08-13T11:39:31+00:00 Hannes Frederic Sowa hannes@stressinduktion.org 2015-03-25T16:07:45+00:00 6caabe4c7dab391fcd7ee36e6cba75697b9e7871 commit 5a352dd0a3aac03b443c94828dfd7144261c8636 upstream. As namespaces are sometimes used with overlapping ip address ranges, we should also use the namespace as input to the hash to select the ip fragmentation counter bucket. Cc: Eric Dumazet <edumazet@google.com> Cc: Flavio Leitner <fbl@redhat.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 5a352dd0a3aac03b443c94828dfd7144261c8636 upstream.

As namespaces are sometimes used with overlapping ip address ranges,
we should also use the namespace as input to the hash to select the ip
fragmentation counter bucket.

Cc: Eric Dumazet <edumazet@google.com>
Cc: Flavio Leitner <fbl@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ipv4: hash net ptr into fragmentation bucket selection 2019-08-13T11:39:30+00:00 Hannes Frederic Sowa hannes@stressinduktion.org 2015-03-25T16:07:44+00:00 1c1e2a916e2715188dc0ad492dbe42e6379c1a66 commit b6a7719aedd7e5c0f2df7641aa47386111682df4 upstream. As namespaces are sometimes used with overlapping ip address ranges, we should also use the namespace as input to the hash to select the ip fragmentation counter bucket. Cc: Eric Dumazet <edumazet@google.com> Cc: Flavio Leitner <fbl@redhat.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit b6a7719aedd7e5c0f2df7641aa47386111682df4 upstream.

As namespaces are sometimes used with overlapping ip address ranges,
we should also use the namespace as input to the hash to select the ip
fragmentation counter bucket.

Cc: Eric Dumazet <edumazet@google.com>
Cc: Flavio Leitner <fbl@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ipv6: Make __ipv6_select_ident static 2019-08-13T11:39:30+00:00 Vlad Yasevich vyasevich@gmail.com 2015-02-09T14:38:21+00:00 dbac56343705df2d24e3588a6ef421d386eda7be commit 8381eacf5c3b35cf7755f4bc521c4d56d24c1cd9 upstream. Make __ipv6_select_ident() static as it isn't used outside the file. Fixes: 0508c07f5e0c9 (ipv6: Select fragment id during UFO segmentation if not set.) Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 8381eacf5c3b35cf7755f4bc521c4d56d24c1cd9 upstream.

Make __ipv6_select_ident() static as it isn't used outside
the file.

Fixes: 0508c07f5e0c9 (ipv6: Select fragment id during UFO segmentation if not set.)
Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ipv6: Select fragment id during UFO segmentation if not set. 2019-08-13T11:39:29+00:00 Vlad Yasevich vyasevich@gmail.com 2015-02-03T21:36:15+00:00 2e095ca0c58515774e6dd45f1f698682c073237f commit 0508c07f5e0c94f38afd5434e8b2a55b84553077 upstream. If the IPv6 fragment id has not been set and we perform fragmentation due to UFO, select a new fragment id. We now consider a fragment id of 0 as unset and if id selection process returns 0 (after all the pertrubations), we set it to 0x80000000, thus giving us ample space not to create collisions with the next packet we may have to fragment. When doing UFO integrity checking, we also select the fragment id if it has not be set yet. This is stored into the skb_shinfo() thus allowing UFO to function correclty. This patch also removes duplicate fragment id generation code and moves ipv6_select_ident() into the header as it may be used during GSO. Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 0508c07f5e0c94f38afd5434e8b2a55b84553077 upstream.

If the IPv6 fragment id has not been set and we perform
fragmentation due to UFO, select a new fragment id.
We now consider a fragment id of 0 as unset and if id selection
process returns 0 (after all the pertrubations), we set it to
0x80000000, thus giving us ample space not to create collisions
with the next packet we may have to fragment.

When doing UFO integrity checking, we also select the
fragment id if it has not be set yet.   This is stored into
the skb_shinfo() thus allowing UFO to function correclty.

This patch also removes duplicate fragment id generation code
and moves ipv6_select_ident() into the header as it may be
used during GSO.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
sctp: get sctphdr by offset in sctp_compute_cksum 2019-08-13T11:38:44+00:00 Xin Long lucien.xin@gmail.com 2019-03-18T11:47:00+00:00 3ef66b61b37b5e28dad11f3c3937f8be647e0e07 commit 273160ffc6b993c7c91627f5a84799c66dfe4dee upstream. sctp_hdr(skb) only works when skb->transport_header is set properly. But in Netfilter, skb->transport_header for ipv6 is not guaranteed to be right value for sctphdr. It would cause to fail to check the checksum for sctp packets. So fix it by using offset, which is always right in all places. v1->v2: - Fix the changelog. Fixes: e6d8b64b34aa ("net: sctp: fix and consolidate SCTP checksumming code") Reported-by: Li Shuang <shuali@redhat.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 273160ffc6b993c7c91627f5a84799c66dfe4dee upstream.

sctp_hdr(skb) only works when skb->transport_header is set properly.

But in Netfilter, skb->transport_header for ipv6 is not guaranteed
to be right value for sctphdr. It would cause to fail to check the
checksum for sctp packets.

So fix it by using offset, which is always right in all places.

v1->v2:
  - Fix the changelog.

Fixes: e6d8b64b34aa ("net: sctp: fix and consolidate SCTP checksumming code")
Reported-by: Li Shuang <shuali@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
netns: provide pure entropy for net_hash_mix() 2019-07-09T21:04:22+00:00 Eric Dumazet edumazet@google.com 2019-03-27T15:21:30+00:00 188da790e1f4d164bcfdea486e91fd47e1ba59c5 commit 355b98553789b646ed97ad801a619ff898471b92 upstream. net_hash_mix() currently uses kernel address of a struct net, and is used in many places that could be used to reveal this address to a patient attacker, thus defeating KASLR, for the typical case (initial net namespace, &init_net is not dynamically allocated) I believe the original implementation tried to avoid spending too many cycles in this function, but security comes first. Also provide entropy regardless of CONFIG_NET_NS. Fixes: 0b4419162aa6 ("netns: introduce the net_hash_mix "salt" for hashes") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Amit Klein <aksecurity@gmail.com> Reported-by: Benny Pinkas <benny@pinkas.net> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 355b98553789b646ed97ad801a619ff898471b92 upstream.

net_hash_mix() currently uses kernel address of a struct net,
and is used in many places that could be used to reveal this
address to a patient attacker, thus defeating KASLR, for
the typical case (initial net namespace, &init_net is
not dynamically allocated)

I believe the original implementation tried to avoid spending
too many cycles in this function, but security comes first.

Also provide entropy regardless of CONFIG_NET_NS.

Fixes: 0b4419162aa6 ("netns: introduce the net_hash_mix "salt" for hashes")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Amit Klein <aksecurity@gmail.com>
Reported-by: Benny Pinkas <benny@pinkas.net>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
gro_cells: make sure device is up in gro_cells_receive() 2019-07-09T21:04:15+00:00 Eric Dumazet edumazet@google.com 2019-03-10T17:39:37+00:00 415f08eb363a0204fb185743469f500e120c6618 commit 2a5ff07a0eb945f291e361aa6f6becca8340ba46 upstream. We keep receiving syzbot reports [1] that show that tunnels do not play the rcu/IFF_UP rules properly. At device dismantle phase, gro_cells_destroy() will be called only after a full rcu grace period is observed after IFF_UP has been cleared. This means that IFF_UP needs to be tested before queueing packets into netif_rx() or gro_cells. This patch implements the test in gro_cells_receive() because too many callers do not seem to bother enough. [1] BUG: unable to handle kernel paging request at fffff4ca0b9ffffe PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 5.0.0+ #97 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net RIP: 0010:__skb_unlink include/linux/skbuff.h:1929 [inline] RIP: 0010:__skb_dequeue include/linux/skbuff.h:1945 [inline] RIP: 0010:__skb_queue_purge include/linux/skbuff.h:2656 [inline] RIP: 0010:gro_cells_destroy net/core/gro_cells.c:89 [inline] RIP: 0010:gro_cells_destroy+0x19d/0x360 net/core/gro_cells.c:78 Code: 03 42 80 3c 20 00 0f 85 53 01 00 00 48 8d 7a 08 49 8b 47 08 49 c7 07 00 00 00 00 48 89 f9 49 c7 47 08 00 00 00 00 48 c1 e9 03 <42> 80 3c 21 00 0f 85 10 01 00 00 48 89 c1 48 89 42 08 48 c1 e9 03 RSP: 0018:ffff8880aa3f79a8 EFLAGS: 00010a02 RAX: 00ffffffffffffe8 RBX: ffffe8ffffc64b70 RCX: 1ffff8ca0b9ffffe RDX: ffffc6505cffffe8 RSI: ffffffff858410ca RDI: ffffc6505cfffff0 RBP: ffff8880aa3f7a08 R08: ffff8880aa3e8580 R09: fffffbfff1263645 R10: fffffbfff1263644 R11: ffffffff8931b223 R12: dffffc0000000000 R13: 0000000000000000 R14: ffffe8ffffc64b80 R15: ffffe8ffffc64b75 kobject: 'loop2' (000000004bd7d84a): kobject_uevent_env FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffff4ca0b9ffffe CR3: 0000000094941000 CR4: 00000000001406f0 Call Trace: kobject: 'loop2' (000000004bd7d84a): fill_kobj_path: path = '/devices/virtual/block/loop2' ip_tunnel_dev_free+0x19/0x60 net/ipv4/ip_tunnel.c:1010 netdev_run_todo+0x51c/0x7d0 net/core/dev.c:8970 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:116 ip_tunnel_delete_nets+0x423/0x5f0 net/ipv4/ip_tunnel.c:1124 vti_exit_batch_net+0x23/0x30 net/ipv4/ip_vti.c:495 ops_exit_list.isra.0+0x105/0x160 net/core/net_namespace.c:156 cleanup_net+0x3fb/0x960 net/core/net_namespace.c:551 process_one_work+0x98e/0x1790 kernel/workqueue.c:2173 worker_thread+0x98/0xe40 kernel/workqueue.c:2319 kthread+0x357/0x430 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Modules linked in: CR2: fffff4ca0b9ffffe [ end trace 513fc9c1338d1cb3 ] RIP: 0010:__skb_unlink include/linux/skbuff.h:1929 [inline] RIP: 0010:__skb_dequeue include/linux/skbuff.h:1945 [inline] RIP: 0010:__skb_queue_purge include/linux/skbuff.h:2656 [inline] RIP: 0010:gro_cells_destroy net/core/gro_cells.c:89 [inline] RIP: 0010:gro_cells_destroy+0x19d/0x360 net/core/gro_cells.c:78 Code: 03 42 80 3c 20 00 0f 85 53 01 00 00 48 8d 7a 08 49 8b 47 08 49 c7 07 00 00 00 00 48 89 f9 49 c7 47 08 00 00 00 00 48 c1 e9 03 <42> 80 3c 21 00 0f 85 10 01 00 00 48 89 c1 48 89 42 08 48 c1 e9 03 RSP: 0018:ffff8880aa3f79a8 EFLAGS: 00010a02 RAX: 00ffffffffffffe8 RBX: ffffe8ffffc64b70 RCX: 1ffff8ca0b9ffffe RDX: ffffc6505cffffe8 RSI: ffffffff858410ca RDI: ffffc6505cfffff0 RBP: ffff8880aa3f7a08 R08: ffff8880aa3e8580 R09: fffffbfff1263645 R10: fffffbfff1263644 R11: ffffffff8931b223 R12: dffffc0000000000 kobject: 'loop3' (00000000e4ee57a6): kobject_uevent_env R13: 0000000000000000 R14: ffffe8ffffc64b80 R15: ffffe8ffffc64b75 FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffff4ca0b9ffffe CR3: 0000000094941000 CR4: 00000000001406f0 Fixes: c9e6bc644e55 ("net: add gro_cells infrastructure") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: - Adjust filename, context - Return type is void] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 2a5ff07a0eb945f291e361aa6f6becca8340ba46 upstream.

We keep receiving syzbot reports [1] that show that tunnels do not play
the rcu/IFF_UP rules properly.

At device dismantle phase, gro_cells_destroy() will be called
only after a full rcu grace period is observed after IFF_UP
has been cleared.

This means that IFF_UP needs to be tested before queueing packets
into netif_rx() or gro_cells.

This patch implements the test in gro_cells_receive() because
too many callers do not seem to bother enough.

[1]
BUG: unable to handle kernel paging request at fffff4ca0b9ffffe
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 5.0.0+ #97
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:__skb_unlink include/linux/skbuff.h:1929 [inline]
RIP: 0010:__skb_dequeue include/linux/skbuff.h:1945 [inline]
RIP: 0010:__skb_queue_purge include/linux/skbuff.h:2656 [inline]
RIP: 0010:gro_cells_destroy net/core/gro_cells.c:89 [inline]
RIP: 0010:gro_cells_destroy+0x19d/0x360 net/core/gro_cells.c:78
Code: 03 42 80 3c 20 00 0f 85 53 01 00 00 48 8d 7a 08 49 8b 47 08 49 c7 07 00 00 00 00 48 89 f9 49 c7 47 08 00 00 00 00 48 c1 e9 03 <42> 80 3c 21 00 0f 85 10 01 00 00 48 89 c1 48 89 42 08 48 c1 e9 03
RSP: 0018:ffff8880aa3f79a8 EFLAGS: 00010a02
RAX: 00ffffffffffffe8 RBX: ffffe8ffffc64b70 RCX: 1ffff8ca0b9ffffe
RDX: ffffc6505cffffe8 RSI: ffffffff858410ca RDI: ffffc6505cfffff0
RBP: ffff8880aa3f7a08 R08: ffff8880aa3e8580 R09: fffffbfff1263645
R10: fffffbfff1263644 R11: ffffffff8931b223 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffe8ffffc64b80 R15: ffffe8ffffc64b75
kobject: 'loop2' (000000004bd7d84a): kobject_uevent_env
FS:  0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffff4ca0b9ffffe CR3: 0000000094941000 CR4: 00000000001406f0
Call Trace:
kobject: 'loop2' (000000004bd7d84a): fill_kobj_path: path = '/devices/virtual/block/loop2'
 ip_tunnel_dev_free+0x19/0x60 net/ipv4/ip_tunnel.c:1010
 netdev_run_todo+0x51c/0x7d0 net/core/dev.c:8970
 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:116
 ip_tunnel_delete_nets+0x423/0x5f0 net/ipv4/ip_tunnel.c:1124
 vti_exit_batch_net+0x23/0x30 net/ipv4/ip_vti.c:495
 ops_exit_list.isra.0+0x105/0x160 net/core/net_namespace.c:156
 cleanup_net+0x3fb/0x960 net/core/net_namespace.c:551
 process_one_work+0x98e/0x1790 kernel/workqueue.c:2173
 worker_thread+0x98/0xe40 kernel/workqueue.c:2319
 kthread+0x357/0x430 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
Modules linked in:
CR2: fffff4ca0b9ffffe
   [ end trace 513fc9c1338d1cb3 ]
RIP: 0010:__skb_unlink include/linux/skbuff.h:1929 [inline]
RIP: 0010:__skb_dequeue include/linux/skbuff.h:1945 [inline]
RIP: 0010:__skb_queue_purge include/linux/skbuff.h:2656 [inline]
RIP: 0010:gro_cells_destroy net/core/gro_cells.c:89 [inline]
RIP: 0010:gro_cells_destroy+0x19d/0x360 net/core/gro_cells.c:78
Code: 03 42 80 3c 20 00 0f 85 53 01 00 00 48 8d 7a 08 49 8b 47 08 49 c7 07 00 00 00 00 48 89 f9 49 c7 47 08 00 00 00 00 48 c1 e9 03 <42> 80 3c 21 00 0f 85 10 01 00 00 48 89 c1 48 89 42 08 48 c1 e9 03
RSP: 0018:ffff8880aa3f79a8 EFLAGS: 00010a02
RAX: 00ffffffffffffe8 RBX: ffffe8ffffc64b70 RCX: 1ffff8ca0b9ffffe
RDX: ffffc6505cffffe8 RSI: ffffffff858410ca RDI: ffffc6505cfffff0
RBP: ffff8880aa3f7a08 R08: ffff8880aa3e8580 R09: fffffbfff1263645
R10: fffffbfff1263644 R11: ffffffff8931b223 R12: dffffc0000000000
kobject: 'loop3' (00000000e4ee57a6): kobject_uevent_env
R13: 0000000000000000 R14: ffffe8ffffc64b80 R15: ffffe8ffffc64b75
FS:  0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffff4ca0b9ffffe CR3: 0000000094941000 CR4: 00000000001406f0

Fixes: c9e6bc644e55 ("net: add gro_cells infrastructure")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16:
 - Adjust filename, context
 - Return type is void]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>