Date:   Tue, 25 Apr 2017 18:38:59 +0200
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     David Ahern <dsa@...ulusnetworks.com>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Mahesh Bandewar <maheshb@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        David Miller <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        James Morris <jmorris@...ei.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Patrick McHardy <kaber@...sh.net>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Cong Wang <xiyou.wangcong@...il.com>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: net: heap out-of-bounds in fib6_clean_node/rt6_fill_node/fib6_age/fib6_prune_clone

On Tue, Apr 25, 2017 at 6:36 PM, Andrey Konovalov <andreyknvl@...gle.com> wrote:
> On Tue, Apr 25, 2017 at 5:56 PM, David Ahern <dsa@...ulusnetworks.com> wrote:
>> On 3/4/17 11:57 AM, Dmitry Vyukov wrote:
>>> ==================================================================
>>> BUG: KASAN: slab-out-of-bounds in rt6_dump_route+0x293/0x2f0
>>> net/ipv6/route.c:3551 at addr ffff88007e523694
>>> Read of size 4 by task syz-executor3/24426
>>> CPU: 2 PID: 24426 Comm: syz-executor3 Not tainted 4.10.0+ #293
>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>> Call Trace:
>>>  __dump_stack lib/dump_stack.c:16 [inline]
>>>  dump_stack+0x2fb/0x3fd lib/dump_stack.c:52
>>>  kasan_object_err+0x1c/0x90 mm/kasan/report.c:166
>>>  print_address_description mm/kasan/report.c:208 [inline]
>>>  kasan_report_error mm/kasan/report.c:292 [inline]
>>>  kasan_report.part.2+0x1b0/0x460 mm/kasan/report.c:314
>>>  kasan_report mm/kasan/report.c:334 [inline]
>>>  __asan_report_load4_noabort+0x29/0x30 mm/kasan/report.c:334
>>>  rt6_dump_route+0x293/0x2f0 net/ipv6/route.c:3551
>>>  fib6_dump_node+0x101/0x1a0 net/ipv6/ip6_fib.c:315
>>>  fib6_walk_continue+0x4b3/0x620 net/ipv6/ip6_fib.c:1576
>>>  fib6_walk+0x91/0xf0 net/ipv6/ip6_fib.c:1621
>>>  fib6_dump_table net/ipv6/ip6_fib.c:374 [inline]
>>>  inet6_dump_fib+0x832/0xea0 net/ipv6/ip6_fib.c:447
>>
>> My expectation is that this one is fixed with the ipv6 patch I have sent
>> (not yet committed). Are you seeing this backtrace with that patch?
>
> Before applying your patch I was hitting reports related to fib6 all the time.
> I've stopped seeing them for some time after I applied your patch.
> However today another one was triggered:

I'll keep fuzzing in the meantime to make sure.
Maybe I'll be able to collect more reports or even another reproducer.

>
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in find_rr_leaf net/ipv6/route.c:722
> [inline] at addr ffff880033dddaa8
> BUG: KASAN: slab-out-of-bounds in rt6_select net/ipv6/route.c:758
> [inline] at addr ffff880033dddaa8
> BUG: KASAN: slab-out-of-bounds in ip6_pol_route+0x1b1e/0x1ba0
> net/ipv6/route.c:1091 at addr ffff880033dddaa8
> Read of size 4 by task syz-executor7/9808
> CPU: 2 PID: 9808 Comm: syz-executor7 Not tainted 4.11.0-rc8+ #268
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:16 [inline]
>  dump_stack+0x192/0x22d lib/dump_stack.c:52
>  kasan_object_err+0x1c/0x70 mm/kasan/report.c:164
>  print_address_description mm/kasan/report.c:202 [inline]
>  kasan_report_error mm/kasan/report.c:291 [inline]
>  kasan_report+0x252/0x510 mm/kasan/report.c:347
>  __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:367
>  find_rr_leaf net/ipv6/route.c:722 [inline]
>  rt6_select net/ipv6/route.c:758 [inline]
>  ip6_pol_route+0x1b1e/0x1ba0 net/ipv6/route.c:1091
>  ip6_pol_route_output+0x4c/0x60 net/ipv6/route.c:1212
>  fib6_rule_action+0x261/0x8a0 net/ipv6/fib6_rules.c:100
>  fib_rules_lookup+0x34b/0xae0 net/core/fib_rules.c:265
>  fib6_rule_lookup+0x175/0x360 net/ipv6/fib6_rules.c:44
>  ip6_route_output_flags+0x260/0x2f0 net/ipv6/route.c:1240
>  ip6_route_output include/net/ip6_route.h:79 [inline]
>  ip6_dst_lookup_tail+0xe59/0x1640 net/ipv6/ip6_output.c:959
>  ip6_dst_lookup_flow+0xb1/0x260 net/ipv6/ip6_output.c:1082
>  ip6_sk_dst_lookup_flow+0x2c6/0x7f0 net/ipv6/ip6_output.c:1113
>  udpv6_sendmsg+0x2350/0x3310 net/ipv6/udp.c:1219
>  inet_sendmsg+0x164/0x490 net/ipv4/af_inet.c:762
>  sock_sendmsg_nosec net/socket.c:633 [inline]
>  sock_sendmsg+0xca/0x110 net/socket.c:643
>  SYSC_sendto+0x660/0x810 net/socket.c:1696
>  SyS_sendto+0x40/0x50 net/socket.c:1664
>  entry_SYSCALL_64_fastpath+0x1a/0xa9
> RIP: 0033:0x4458d9
> RSP: 002b:00007ff3a5343b58 EFLAGS: 00000282 ORIG_RAX: 000000000000002c
> RAX: ffffffffffffffda RBX: 0000000000708000 RCX: 00000000004458d9
> RDX: 0000000000000fa8 RSI: 0000000020000000 RDI: 0000000000000005
> RBP: 0000000000004300 R08: 0000000020006000 R09: 000000000000001c
> R10: 0000000000040000 R11: 0000000000000282 R12: 00000000006e33c0
> R13: 0000000000000005 R14: 0000000000000029 R15: 0000000000000023
> Object at ffff880033ddd940, in cache ip_dst_cache size: 224
> Allocated:
> PID = 9717
>  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:513
>  set_track mm/kasan/kasan.c:525 [inline]
>  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:616
>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:555
>  slab_post_alloc_hook mm/slab.h:456 [inline]
>  slab_alloc_node mm/slub.c:2718 [inline]
>  slab_alloc mm/slub.c:2726 [inline]
>  kmem_cache_alloc+0xa8/0x160 mm/slub.c:2731
>  dst_alloc+0x11b/0x1a0 net/core/dst.c:209
>  rt_dst_alloc+0xf0/0x5d0 net/ipv4/route.c:1497
>  __mkroute_output net/ipv4/route.c:2181 [inline]
>  __ip_route_output_key_hash+0xdc4/0x2930 net/ipv4/route.c:2391
>  __ip_route_output_key include/net/route.h:123 [inline]
>  ip_route_output_flow+0x29/0xa0 net/ipv4/route.c:2477
>  ip_route_output_key include/net/route.h:133 [inline]
>  sctp_v4_get_dst+0x606/0x1420 net/sctp/protocol.c:458
>  sctp_transport_route+0xa8/0x420 net/sctp/transport.c:287
>  sctp_assoc_add_peer+0x5a5/0x1470 net/sctp/associola.c:656
>  sctp_sendmsg+0x18a8/0x3b50 net/sctp/socket.c:1871
>  inet_sendmsg+0x164/0x490 net/ipv4/af_inet.c:762
>  sock_sendmsg_nosec net/socket.c:633 [inline]
>  sock_sendmsg+0xca/0x110 net/socket.c:643
>  SYSC_sendto+0x660/0x810 net/socket.c:1696
>  SyS_sendto+0x40/0x50 net/socket.c:1664
>  entry_SYSCALL_64_fastpath+0x1a/0xa9
> Freed:
> PID = 868
>  save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:513
>  set_track mm/kasan/kasan.c:525 [inline]
>  kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:589
>  slab_free_hook mm/slub.c:1357 [inline]
>  slab_free_freelist_hook mm/slub.c:1379 [inline]
>  slab_free mm/slub.c:2961 [inline]
>  kmem_cache_free+0x72/0x190 mm/slub.c:2983
>  dst_destroy+0x24c/0x390 net/core/dst.c:269
>  dst_free include/net/dst.h:428 [inline]
>  rt_fibinfo_free net/ipv4/fib_semantics.c:155 [inline]
>  free_fib_info_rcu+0x852/0xa10 net/ipv4/fib_semantics.c:214
>  __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
>  rcu_do_batch.isra.65+0x6de/0xbd0 kernel/rcu/tree.c:2879
>  invoke_rcu_callbacks kernel/rcu/tree.c:3142 [inline]
>  __rcu_process_callbacks kernel/rcu/tree.c:3109 [inline]
>  rcu_process_callbacks+0x23f/0x810 kernel/rcu/tree.c:3126
>  __do_softirq+0x253/0x78b kernel/softirq.c:284
> Memory state around the buggy address:
>  ffff880033ddd980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff880033ddda00: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
>>ffff880033ddda80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>                                   ^
>  ffff880033dddb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff880033dddb80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> ==================================================================.
>
>>
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