Re: [syzbot] general protection fault in ethnl_set_plca_cfg

[Dmitry Vyukov]

On Sun, 15 Jan 2023 at 22:37, syzbot
<syzbot+8cf35743af243e5f417e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    60d86034b14e Merge tag 'mlx5-updates-2023-01-10' of git://..
> git tree:       net-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12582c02480000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=de2f853811ba4e08
> dashboard link: https://syzkaller.appspot.com/bug?extid=8cf35743af243e5f417e
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1773adf2480000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=140bc05e480000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/b5b394a217aa/disk-60d86034.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/f129c2da4b3a/vmlinux-60d86034.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/6dbc96a4303d/bzImage-60d86034.xz
>
> The issue was bisected to:
>
> commit 8580e16c28f3f1a1bee87de115157161577334b4
> Author: Piergiorgio Beruto <piergiorgio.beruto@xxxxxxxxx>
> Date:   Mon Jan 9 16:59:39 2023 +0000
>
>     net/ethtool: add netlink interface for the PLCA RS
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10fde136480000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=12fde136480000
> console output: https://syzkaller.appspot.com/x/log.txt?x=14fde136480000

#syz fix: plca.c: fix obvious mistake in checking retval

> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+8cf35743af243e5f417e@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 8580e16c28f3 ("net/ethtool: add netlink interface for the PLCA RS")
>
> general protection fault, probably for non-canonical address 0xdffffc0000000173: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000b98-0x0000000000000b9f]
> CPU: 1 PID: 5067 Comm: syz-executor355 Not tainted 6.2.0-rc2-syzkaller-00378-g60d86034b14e #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
> RIP: 0010:ethnl_set_plca_cfg+0x1c5/0x810 net/ethtool/plca.c:162
> Code: 28 7a f9 4c 8b 7c 24 58 e8 d8 17 c6 ff 49 8d 87 98 0b 00 00 48 89 c2 48 89 44 24 08 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 7d 05 00 00 49 83 bf 98 0b 00 00 00 0f 84 b8 04
> RSP: 0018:ffffc90003cbf470 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: ffffc90003cbf5d8 RCX: 0000000000000000
> RDX: 0000000000000173 RSI: 0000000000000002 RDI: 0000000000000001
> RBP: 1ffff92000797e95 R08: 0000000000000000 R09: ffffffff8e72e917
> R10: fffffbfff1ce5d22 R11: 0000000000000000 R12: 00000000ffffffea
> R13: ffff88801cc43980 R14: ffffc90003cbf618 R15: 0000000000000000
> FS:  00005555563b5300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020001ac0 CR3: 000000007d808000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968
>  genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
>  genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065
>  netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564
>  genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
>  netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
>  netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356
>  netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932
>  sock_sendmsg_nosec net/socket.c:714 [inline]
>  sock_sendmsg+0xd3/0x120 net/socket.c:734
>  ____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
>  ___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
>  __sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7fb1764e4ae9
> Code: 28 c3 e8 5a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd5160add8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb1764e4ae9
> RDX: 0000000000000000 RSI: 0000000020001ac0 RDI: 0000000000000003
> RBP: 00007fb1764a84b0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb1764a8540
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:ethnl_set_plca_cfg+0x1c5/0x810 net/ethtool/plca.c:162
> Code: 28 7a f9 4c 8b 7c 24 58 e8 d8 17 c6 ff 49 8d 87 98 0b 00 00 48 89 c2 48 89 44 24 08 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 7d 05 00 00 49 83 bf 98 0b 00 00 00 0f 84 b8 04
> RSP: 0018:ffffc90003cbf470 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: ffffc90003cbf5d8 RCX: 0000000000000000
> RDX: 0000000000000173 RSI: 0000000000000002 RDI: 0000000000000001
> RBP: 1ffff92000797e95 R08: 0000000000000000 R09: ffffffff8e72e917
> R10: fffffbfff1ce5d22 R11: 0000000000000000 R12: 00000000ffffffea
> R13: ffff88801cc43980 R14: ffffc90003cbf618 R15: 0000000000000000
> FS:  00005555563b5300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020001ac0 CR3: 000000007d808000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>    0:   28 7a f9                sub    %bh,-0x7(%rdx)
>    3:   4c 8b 7c 24 58          mov    0x58(%rsp),%r15
>    8:   e8 d8 17 c6 ff          callq  0xffc617e5
>    d:   49 8d 87 98 0b 00 00    lea    0xb98(%r15),%rax
>   14:   48 89 c2                mov    %rax,%rdx
>   17:   48 89 44 24 08          mov    %rax,0x8(%rsp)
>   1c:   48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
>   23:   fc ff df
>   26:   48 c1 ea 03             shr    $0x3,%rdx
> * 2a:   80 3c 02 00             cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
>   2e:   0f 85 7d 05 00 00       jne    0x5b1
>   34:   49 83 bf 98 0b 00 00    cmpq   $0x0,0xb98(%r15)
>   3b:   00
>   3c:   0f                      .byte 0xf
>   3d:   84                      .byte 0x84
>   3e:   b8                      .byte 0xb8
>   3f:   04                      .byte 0x4
>
>
> ---
> This report 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@xxxxxxxxxxxxxxxx.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>
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