linux-kernel - Re: KASAN: use-after-free Write in tls_push

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Message-ID: <bb81a2ef-7908-844d-3161-213973342ddb@mellanox.com>
Date:   Thu, 12 Jul 2018 06:44:55 -0400
From:   Boris Pismenny <borisp@...lanox.com>
To:     syzbot <syzbot+6c4e6ecbf9a2797be67c@...kaller.appspotmail.com>,
        aviadye@...lanox.com, davejwatson@...com, davem@...emloft.net,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: KASAN: use-after-free Write in tls_push_record (2)

It seems to me that the crash here is due to write_space being called 
after the close system call. Maybe the correct solution is to move the 
TX software state to be released in sk_destruct. As we already do for 
the device state (see tls_device.c).

Is anyone looking into this one?

On 7/11/2018 8:49 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    1e09177acae3 Merge tag 'mips_fixes_4.18_3' of 
> git://git.ke..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=128903b2400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=25856fac4e580aa7
> dashboard link: 
> https://syzkaller.appspot.com/bug?extid=6c4e6ecbf9a2797be67c
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=12312678400000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13ef76c2400000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+6c4e6ecbf9a2797be67c@...kaller.appspotmail.com
> 
> RDX: 00000000fffffdef RSI: 00000000200005c0 RDI: 0000000000000003
> RBP: 00000000006cb018 R08: 0000000020000000 R09: 000000000000001c
> R10: 0000000000000040 R11: 0000000000000212 R12: 0000000000000005
> R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
> ==================================================================
> BUG: KASAN: use-after-free in tls_fill_prepend include/net/tls.h:339 
> [inline]
> BUG: KASAN: use-after-free in tls_push_record+0x1091/0x1400 
> net/tls/tls_sw.c:239
> Write of size 1 at addr ffff8801ae430000 by task syz-executor589/4567
> 
> CPU: 0 PID: 4567 Comm: syz-executor589 Not tainted 4.18.0-rc4+ #141
> 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+0x1c9/0x2b4 lib/dump_stack.c:113
>   print_address_description+0x6c/0x20b mm/kasan/report.c:256
>   kasan_report_error mm/kasan/report.c:354 [inline]
>   kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
>   __asan_report_store1_noabort+0x17/0x20 mm/kasan/report.c:435
>   tls_fill_prepend include/net/tls.h:339 [inline]
>   tls_push_record+0x1091/0x1400 net/tls/tls_sw.c:239
>   tls_sw_push_pending_record+0x22/0x30 net/tls/tls_sw.c:276
>   tls_handle_open_record net/tls/tls_main.c:164 [inline]
>   tls_sk_proto_close+0x74c/0xae0 net/tls/tls_main.c:264
>   inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427
>   inet6_release+0x50/0x70 net/ipv6/af_inet6.c:459
>   __sock_release+0xd7/0x260 net/socket.c:599
>   sock_close+0x19/0x20 net/socket.c:1150
>   __fput+0x355/0x8b0 fs/file_table.c:209
>   ____fput+0x15/0x20 fs/file_table.c:243
>   task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
>   exit_task_work include/linux/task_work.h:22 [inline]
>   do_exit+0x1b08/0x2750 kernel/exit.c:865
>   do_group_exit+0x177/0x440 kernel/exit.c:968
>   __do_sys_exit_group kernel/exit.c:979 [inline]
>   __se_sys_exit_group kernel/exit.c:977 [inline]
>   __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:977
>   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x43f358
> Code: Bad RIP value.
> RSP: 002b:00007fff51750198 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043f358
> RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
> RBP: 00000000004bf448 R08: 00000000000000e7 R09: ffffffffffffffd0
> R10: 0000000000000040 R11: 0000000000000246 R12: 0000000000000001
> R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000
> 
> The buggy address belongs to the page:
> page:ffffea0006b90c00 count:0 mapcount:-128 mapping:0000000000000000 
> index:0x0
> flags: 0x2fffc0000000000()
> raw: 02fffc0000000000 ffffea0006b96408 ffff88021fffac18 0000000000000000
> raw: 0000000000000000 0000000000000003 00000000ffffff7f 0000000000000000
> page dumped because: kasan: bad access detected
> 
> Memory state around the buggy address:
>   ffff8801ae42ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>   ffff8801ae42ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>> ffff8801ae430000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>                     ^
>   ffff8801ae430080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>   ffff8801ae430100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ==================================================================
> 
> 
> ---
> 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@...glegroups.com.
> 
> 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