Date:   Sat, 3 Jun 2017 05:17:47 +0000
From:   "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>
To:     "edumazet@...gle.com" <edumazet@...gle.com>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: net: icmp vs udp_poll race?

Hi all,

On the latest linux-next I'm seeing issues that look like an icmp
socket destruction racing with poll(). It manifests in two ways, first:

BUG: KASAN: slab-out-of-bounds in skb_queue_empty include/linux/skbuff.h:1197 [inline]
BUG: KASAN: slab-out-of-bounds in udp_poll+0x5fb/0x6f0 net/ipv4/udp.c:2443
Read of size 8 at addr ffff88006941a200 by task syz-executor5/9052

CPU: 2 PID: 9052 Comm: syz-executor5 Not tainted 4.12.0-rc3-next-20170601+ #47
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x115/0x1d1 lib/dump_stack.c:52
 print_address_description+0xe7/0x370 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x1b0/0x450 mm/kasan/report.c:408
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 skb_queue_empty include/linux/skbuff.h:1197 [inline]
 udp_poll+0x5fb/0x6f0 net/ipv4/udp.c:2443
 sock_poll+0x169/0x410 net/socket.c:1101
 do_pollfd fs/select.c:825 [inline]
 do_poll fs/select.c:875 [inline]
 do_sys_poll+0x7a7/0x13b0 fs/select.c:969
 SYSC_poll fs/select.c:1027 [inline]
 SyS_poll+0x106/0x460 fs/select.c:1015
 do_syscall_64+0x275/0x810 arch/x86/entry/common.c:284
 entry_SYSCALL64_slow_path+0x25/0x25
RIP: 0033:0x451429
RSP: 002b:00007fee2df0dc08 EFLAGS: 00000216 ORIG_RAX: 0000000000000007
RAX: ffffffffffffffda RBX: 0000000020000fb0 RCX: 0000000000451429
RDX: 000000000000001f RSI: 000000000000000a RDI: 0000000020000fb0
RBP: 0000000000718000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000216 R12: 00000000ffffffff
R13: 000000000000000a R14: 00000000000003c4 R15: 00007fee2df0e700

Allocated by task 9052:
 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+0xae/0xe0 mm/kasan/kasan.c:617
 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:2712 [inline]
 slab_alloc mm/slub.c:2720 [inline]
 kmem_cache_alloc+0x12f/0x610 mm/slub.c:2725
 sk_prot_alloc+0x6e/0x300 net/core/sock.c:1422
 sk_alloc+0x82/0x880 net/core/sock.c:1484
 inet_create+0x519/0x11b0 net/ipv4/af_inet.c:318
 __sock_create+0x52e/0xa50 net/socket.c:1249
 sock_create net/socket.c:1289 [inline]
 SYSC_socket net/socket.c:1319 [inline]
 SyS_socket+0x105/0x260 net/socket.c:1299
 do_syscall_64+0x275/0x810 arch/x86/entry/common.c:284
 return_from_SYSCALL_64+0x0/0x7a

Freed by task 8076:
 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+0x72/0xc0 mm/kasan/kasan.c:590
 slab_free_hook mm/slub.c:1357 [inline]
 slab_free_freelist_hook mm/slub.c:1379 [inline]
 slab_free mm/slub.c:2955 [inline]
 kmem_cache_free+0xec/0x630 mm/slub.c:2977
 sk_prot_free net/core/sock.c:1465 [inline]
 __sk_destruct+0x6a1/0xb40 net/core/sock.c:1546
 sk_destruct+0x57/0xb0 net/core/sock.c:1554
 __sk_free+0x62/0x260 net/core/sock.c:1562
 sk_free+0x28/0x40 net/core/sock.c:1573
 sock_put include/net/sock.h:1655 [inline]
 sk_common_release+0x241/0x3c0 net/core/sock.c:2902
 ping_close+0x15/0x20 net/ipv4/ping.c:295
 inet_release+0x108/0x240 net/ipv4/af_inet.c:425
 sock_release+0x96/0x260 net/socket.c:597
 SYSC_socketpair net/socket.c:1436 [inline]
 SyS_socketpair+0x522/0x710 net/socket.c:1340
 do_syscall_64+0x275/0x810 arch/x86/entry/common.c:284
 return_from_SYSCALL_64+0x0/0x7a

The buggy address belongs to the object at ffff880069419c40
 which belongs to the cache PING of size 1392
The buggy address is located 80 bytes to the right of
 1392-byte region [ffff880069419c40, ffff88006941a1b0)
The buggy address belongs to the page:
page:ffffea0001a50600 count:1 mapcount:0 mapping:          (null) index:0xffff88006941d440 compound_mapcount: 0
flags: 0x5fffc0000008100(slab|head)
raw: 05fffc0000008100 0000000000000000 ffff88006941d440 0000000100120005
raw: ffff88006c5ba490 ffff88006c5ba490 ffff88006b197c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88006941a100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88006941a180: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff88006941a200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff88006941a280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88006941a300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb

And second:

INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 3 PID: 12664 Comm: syz-executor7 Not tainted 4.12.0-rc3-next-20170601+ #47
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1ubuntu1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x115/0x1d1 lib/dump_stack.c:52
 register_lock_class+0x5a5/0x2ce0 kernel/locking/lockdep.c:755
 __lock_acquire+0x220/0x4f90 kernel/locking/lockdep.c:3255
 lock_acquire+0x1f8/0x6e0 kernel/locking/lockdep.c:3855
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x40/0x90 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:304 [inline]
 first_packet_length+0xcf/0x7b0 net/ipv4/udp.c:1401
 udp_poll+0x4c6/0x6f0 net/ipv4/udp.c:2450
 sock_poll+0x169/0x410 net/socket.c:1101
 do_pollfd fs/select.c:825 [inline]
 do_poll fs/select.c:875 [inline]
 do_sys_poll+0x7a7/0x13b0 fs/select.c:969
 SYSC_ppoll fs/select.c:1078 [inline]
 SyS_ppoll+0x22e/0x540 fs/select.c:1049
 do_syscall_64+0x275/0x810 arch/x86/entry/common.c:284
 entry_SYSCALL64_slow_path+0x25/0x25
RIP: 0033:0x451429
RSP: 002b:00007fa135ce5c08 EFLAGS: 00000216 ORIG_RAX: 000000000000010f
RAX: ffffffffffffffda RBX: 0000000020001ff8 RCX: 0000000000451429
RDX: 0000000020000000 RSI: 0000000000000001 RDI: 0000000020001ff8
RBP: 0000000000718000 R08: 0000000000000008 R09: 0000000000000000
R10: 0000000020005ff8 R11: 0000000000000216 R12: 00000000ffffffff
R13: 0000000000000001 R14: 00000000000003c5 R15: 00007fa135ce6700

Syzkaller reproduces these once in a while using:

mmap(&(0x7f0000000000/0x6000)=nil, (0x6000), 0x3, 0x32, 0xffffffffffffffff, 0x0)
r0 = socket$icmp6(0xa, 0x2, 0x3a)
ppoll(&(0x7f0000002000-0x8)=[{r0, 0x201, 0x0}], 0x1, &(0x7f0000000000)={0x0, 0x989680}, &(0x7f0000006000-0x8)={0x101}, 0x8)

-- 

Thanks,
Sasha

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