Re: KASAN: use-after-free Read in tipc_group_is_open

[Cong Wang]

On Mon, Jan 15, 2018 at 7:58 PM, syzbot
<syzbot+799dafde0286795858ac@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Hello,
>
> syzkaller hit the following crash on
> 594831a8aba3fd045c3212a3e3bb9788c77b989d
> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers
>
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+799dafde0286795858ac@xxxxxxxxxxxxxxxxxxxxxxxxx
> It will help syzbot understand when the bug is fixed. See footer for
> details.
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>
> ==================================================================
> BUG: KASAN: use-after-free in tipc_group_is_open+0x3a/0x40
> net/tipc/group.c:106
> Read of size 1 at addr ffff8801d89f7378 by task syzkaller275009/3704
>
> CPU: 0 PID: 3704 Comm: syzkaller275009 Not tainted 4.15.0-rc7+ #190
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:17 [inline]
>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>  print_address_description+0x73/0x250 mm/kasan/report.c:252
>  kasan_report_error mm/kasan/report.c:351 [inline]
>  kasan_report+0x25b/0x340 mm/kasan/report.c:409
>  __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:427
>  tipc_group_is_open+0x3a/0x40 net/tipc/group.c:106
>  tipc_poll+0x364/0x4d0 net/tipc/socket.c:740


commit eb929a91b213d2a72c5a8b4af9a1acf63bfb8287
Author: Jon Maloy <jon.maloy@xxxxxxxxxxxx>
Date:   Mon Jan 8 21:03:31 2018 +0100

    tipc: improve poll() for group member socket

Apparently Jon's commit doesn't fix this. I also don't understand why
Jon believes sock_poll_wait() could sync with setsockopt path...



>  sock_poll+0x141/0x320 net/socket.c:1111
>  do_pollfd fs/select.c:822 [inline]
>  do_poll fs/select.c:872 [inline]
>  do_sys_poll+0x715/0x10b0 fs/select.c:966
>  SYSC_poll fs/select.c:1024 [inline]
>  SyS_poll+0x10d/0x450 fs/select.c:1012
>  entry_SYSCALL_64_fastpath+0x23/0x9a
> RIP: 0033:0x446129
> RSP: 002b:00007f0f2df96db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000007
> RAX: ffffffffffffffda RBX: 00000000006dbc54 RCX: 0000000000446129
> RDX: 0000000000007fff RSI: 000000000000000a RDI: 0000000020ef5000
> RBP: 00000000006dbc50 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffc07e2923f R14: 00007f0f2df979c0 R15: 0000000000000007
>
> Allocated by task 3702:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>  set_track mm/kasan/kasan.c:459 [inline]
>  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
>  kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3610
>  kmalloc include/linux/slab.h:499 [inline]
>  kzalloc include/linux/slab.h:688 [inline]
>  tipc_group_create+0x144/0x900 net/tipc/group.c:180
>  tipc_sk_join net/tipc/socket.c:2762 [inline]
>  tipc_setsockopt+0x274/0xce0 net/tipc/socket.c:2877
>  SYSC_setsockopt net/socket.c:1823 [inline]
>  SyS_setsockopt+0x189/0x360 net/socket.c:1802
>  entry_SYSCALL_64_fastpath+0x23/0x9a
>
> Freed by task 3702:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
>  set_track mm/kasan/kasan.c:459 [inline]
>  kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
>  __cache_free mm/slab.c:3488 [inline]
>  kfree+0xd6/0x260 mm/slab.c:3803
>  tipc_group_delete+0x2c8/0x3d0 net/tipc/group.c:234
>  tipc_sk_join net/tipc/socket.c:2775 [inline]
>  tipc_setsockopt+0xaa9/0xce0 net/tipc/socket.c:2877
>  SYSC_setsockopt net/socket.c:1823 [inline]
>  SyS_setsockopt+0x189/0x360 net/socket.c:1802
>  entry_SYSCALL_64_fastpath+0x23/0x9a
>
> The buggy address belongs to the object at ffff8801d89f7300
>  which belongs to the cache kmalloc-128 of size 128
> The buggy address is located 120 bytes inside of
>  128-byte region [ffff8801d89f7300, ffff8801d89f7380)
> The buggy address belongs to the page:
> page:ffffea0007627dc0 count:1 mapcount:0 mapping:ffff8801d89f7000 index:0x0
> flags: 0x2fffc0000000100(slab)
> raw: 02fffc0000000100 ffff8801d89f7000 0000000000000000 0000000100000015
> raw: ffffea0007622720 ffffea0007627ce0 ffff8801dac00640 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8801d89f7200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>  ffff8801d89f7280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>>
>> ffff8801d89f7300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>
>                                                                 ^
>  ffff8801d89f7380: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
>  ffff8801d89f7400: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
> ==================================================================
>
>
> ---
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