RE: KASAN: use-after-free Read in tipc_group_cong

From: Jon Maloy
Date: Wed Dec 12 2018 - 19:31:45 EST

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> -----Original Message-----
> From: syzbot <syzbot+9845fed98688e01f431e@xxxxxxxxxxxxxxxxxxxxxxxxx>
> Sent: 12-Dec-18 06:11
> To: davem@xxxxxxxxxxxxx; Jon Maloy <jon.maloy@xxxxxxxxxxxx>; linux-
> kernel@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; syzkaller-
> bugs@xxxxxxxxxxxxxxxx; tipc-discussion@xxxxxxxxxxxxxxxxxxxxx;
> ying.xue@xxxxxxxxxxxxx
> Subject: KASAN: use-after-free Read in tipc_group_cong

This seems to be an effect of the same bug as reported in
https://syzkaller.appspot.com/bug?extid=10a9db47c3a0e13eb31c

Cong posted a fix for that one. Did you see the crash after applying his patch?

///jon

>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: f5d582777bcb Merge branch 'for-linus' of git://git.kernel...
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1705d525400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=c8970c89a0efbb23
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=9845fed98688e01f431e
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=101b6ba3400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+9845fed98688e01f431e@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> 8021q: adding VLAN 0 to HW filter on device team0
> 8021q: adding VLAN 0 to HW filter on device team0
> audit: type=1400 audit(1544592509.246:38): avc: denied { associate } for
> pid=6204 comm="syz-executor5" name="syz5"
> scontext=unconfined_u:object_r:unlabeled_t:s0
> tcontext=system_u:object_r:unlabeled_t:s0 tclass=filesystem permissive=1
> ==========================================================
> ========
> BUG: KASAN: use-after-free in tipc_group_find_dest net/tipc/group.c:255
> [inline]
> BUG: KASAN: use-after-free in tipc_group_cong+0x566/0x5d0
> net/tipc/group.c:416
> Read of size 8 at addr ffff8881c59f5000 by task syz-executor4/10565
>
> CPU: 1 PID: 10565 Comm: syz-executor4 Not tainted 4.20.0-rc6+ #151
> Hardware name: Google Google Compute Engine/Google Compute Engine,
> BIOS Google 01/01/2011 Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x244/0x39d lib/dump_stack.c:113
> print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
> kasan_report_error mm/kasan/report.c:354 [inline]
> kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
> tipc_group_find_dest net/tipc/group.c:255 [inline]
> tipc_group_cong+0x566/0x5d0 net/tipc/group.c:416
> tipc_send_group_anycast+0x9bb/0xc80 net/tipc/socket.c:972
> __tipc_sendmsg+0x12b1/0x1d40 net/tipc/socket.c:1309
> tipc_sendmsg+0x50/0x70 net/tipc/socket.c:1272
> sock_sendmsg_nosec net/socket.c:621 [inline]
> sock_sendmsg+0xd5/0x120 net/socket.c:631
> ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
> __sys_sendmsg+0x11d/0x280 net/socket.c:2154
> __do_sys_sendmsg net/socket.c:2163 [inline]
> __se_sys_sendmsg net/socket.c:2161 [inline]
> __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x457679
> Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83
> cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f813d748c78 EFLAGS: 00000246 ORIG_RAX:
> 000000000000002e
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457679
> RDX: 0000000000000000 RSI: 00000000200006c0 RDI: 0000000000000005
> RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f813d7496d4
> R13: 00000000004c44dd R14: 00000000004d74c8 R15: 00000000ffffffff
>
> Allocated by task 10551:
> save_stack+0x43/0xd0 mm/kasan/kasan.c:448
> set_track mm/kasan/kasan.c:460 [inline]
> kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
> kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
> kmalloc include/linux/slab.h:546 [inline]
> kzalloc include/linux/slab.h:741 [inline]
> tipc_group_create+0x152/0xa70 net/tipc/group.c:171
> tipc_sk_join net/tipc/socket.c:2829 [inline]
> tipc_setsockopt+0x2d1/0xd70 net/tipc/socket.c:2944
> __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
> __do_sys_setsockopt net/socket.c:1913 [inline]
> __se_sys_setsockopt net/socket.c:1910 [inline]
> __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Freed by task 10567:
> save_stack+0x43/0xd0 mm/kasan/kasan.c:448
> set_track mm/kasan/kasan.c:460 [inline]
> __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
> kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
> __cache_free mm/slab.c:3498 [inline]
> kfree+0xcf/0x230 mm/slab.c:3817
> tipc_group_delete+0x2e4/0x3f0 net/tipc/group.c:227
> tipc_sk_leave+0x113/0x220 net/tipc/socket.c:2863
> tipc_setsockopt+0x97d/0xd70 net/tipc/socket.c:2947
> __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
> __do_sys_setsockopt net/socket.c:1913 [inline]
> __se_sys_setsockopt net/socket.c:1910 [inline]
> __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> The buggy address belongs to the object at ffff8881c59f5000
> which belongs to the cache kmalloc-192 of size 192 The buggy address is
> located 0 bytes inside of
> 192-byte region [ffff8881c59f5000, ffff8881c59f50c0) The buggy address
> belongs to the page:
> page:ffffea0007167d40 count:1 mapcount:0 mapping:ffff8881da800040
> index:0x0
> flags: 0x2fffc0000000200(slab)
> raw: 02fffc0000000200 ffffea0007160488 ffffea00071aff08 ffff8881da800040
> raw: 0000000000000000 ffff8881c59f5000 0000000100000010
> 0000000000000000 page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
> ffff8881c59f4f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8881c59f4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > ffff8881c59f5000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff8881c59f5080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ffff8881c59f5100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ==========================================================
> ========
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches

Next message: David Miller: "Re: [PATCH net-next] bnxt: remove printing of hwrm message"
Previous message: Javier Barrio: "[PATCH] quota: Lock s_umount in exclusive mode for Q_XQUOTA{ON,OFF} quotactls."
In reply to: syzbot: "KASAN: use-after-free Read in tipc_group_cong"
Next in thread: Dmitry Vyukov: "Re: KASAN: use-after-free Read in tipc_group_cong"
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