Re: BUG: unable to handle kernel paging request in can_rcv_filter

[Eric Dumazet]

On Tue, Dec 6, 2022 at 4:26 PM Wei Chen <harperchen1110@xxxxxxxxx> wrote:
>
> Dear Linux Developers,
>
> Recently, when using our tool to fuzz kernel, the following crash was triggered.
>
> HEAD commit: 147307c69ba
> git tree: linux-next
> compiler: clang 12.0.0
> console output:
> https://drive.google.com/file/d/1_c7TZ6WzCT-VLBimUP3xnkMpJPhjOAPY/view?usp=share_link
> kernel config: https://drive.google.com/file/d/1NAf4S43d9VOKD52xbrqw-PUP1Mbj8z-S/view?usp=share_link
>
> Unfortunately, I didn't have a reproducer for this crash.

Well, public syzbot instance has something better, with a repro....

syzbot found the following issue on:

HEAD commit:    e3cb714fb489 Merge branch 'for-next/core' into for-kernelci
git tree:
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=16e55ae3880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ec7118319bfb771e
dashboard link: https://syzkaller.appspot.com/bug?extid=2d7f58292cb5b29eb5ad
compiler:       Debian clang version
13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld
(GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1164b38d880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11f61223880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/832eb1866f2c/disk-e3cb714f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5fd572b7d96d/vmlinux-e3cb714f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/34c82908beda/Image-e3cb714f.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2d7f58292cb5b29eb5ad@xxxxxxxxxxxxxxxxxxxxxxxxx

>
> I'm wondering if there is a data race between can_receive and
> sock_close, which leads to the invalid null value of dev and
> dev_rcv_lists. I hope the following report is helpful.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: Wei Chen <harperchen1110@xxxxxxxxx>
>
> BUG: unable to handle page fault for address: 0000000000006020
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 132110067 P4D 132110067 PUD 1320b6067 PMD 0
> Oops: 0000 [#1] PREEMPT SMP
> CPU: 0 PID: 13844 Comm: syz-executor.0 Not tainted 6.1.0-rc5-next-20221118 #2
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
> RIP: 0010:can_rcv_filter+0x44/0x4e0 net/can/af_can.c:584
> Code: 00 00 00 e8 3e 86 0f fd 49 8b 9e d8 00 00 00 48 89 df e8 af 81
> 0f fd 44 8b 23 48 8d bd 20 60 00 00 e8 a0 81 0f fd 48 89 2c 24 <8b> 9d
> 20 60 00 00 45 31 ed 31 ff 89 de e8 9a 1c fc fc 85 db 0f 84
> RSP: 0018:ffffc90000003d50 EFLAGS: 00010246
> RAX: ffff88813bc274d8 RBX: ffff8881310c5a10 RCX: ffffffff842b9940
> RDX: 0000000000000522 RSI: 0000000000000000 RDI: 0000000000006020
> RBP: 0000000000000000 R08: 0000000000006023 R09: 0000000000000000
> R10: 0001ffffffffffff R11: 00018881310c5a04 R12: 0000000000000000
> R13: ffff888106fb8880 R14: ffff8881308cba00 R15: 0000000000000000
> FS:  00007fc9368b0700(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000006020 CR3: 0000000132249000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000020000180 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
> Call Trace:
>  <IRQ>
>  can_receive+0x182/0x1f0 net/can/af_can.c:664
>  canfd_rcv+0x9a/0x120 net/can/af_can.c:703
>  __netif_receive_skb_one_core net/core/dev.c:5482 [inline]
>  __netif_receive_skb+0x8b/0x1b0 net/core/dev.c:5596
>  process_backlog+0x23f/0x3b0 net/core/dev.c:5924
>  __napi_poll+0x65/0x420 net/core/dev.c:6485
>  napi_poll net/core/dev.c:6552 [inline]
>  net_rx_action+0x37e/0x730 net/core/dev.c:6663
>  __do_softirq+0xf2/0x2c9 kernel/softirq.c:571
>  do_softirq+0xb1/0xf0 kernel/softirq.c:472
>  </IRQ>
>  <TASK>
>  __local_bh_enable_ip+0x6f/0x80 kernel/softirq.c:396
>  local_bh_enable+0x1b/0x20 include/linux/bottom_half.h:33
>  netif_rx+0x63/0x1c0 net/core/dev.c:5003
>  can_send+0x521/0x5b0 net/can/af_can.c:286
>  bcm_can_tx+0x2f0/0x3f0 net/can/bcm.c:302
>  bcm_tx_setup net/can/bcm.c:1020 [inline]
>  bcm_sendmsg+0x1f78/0x2c50 net/can/bcm.c:1351
>  sock_sendmsg_nosec net/socket.c:714 [inline]
>  sock_sendmsg net/socket.c:734 [inline]
>  ____sys_sendmsg+0x38f/0x500 net/socket.c:2476
>  ___sys_sendmsg net/socket.c:2530 [inline]
>  __sys_sendmsg+0x197/0x230 net/socket.c:2559
>  __do_sys_sendmsg net/socket.c:2568 [inline]
>  __se_sys_sendmsg net/socket.c:2566 [inline]
>  __x64_sys_sendmsg+0x42/0x50 net/socket.c:2566
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x4697f9
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 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 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fc9368afc48 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 000000000077bf80 RCX: 00000000004697f9
> RDX: 0000000000000000 RSI: 0000000020000380 RDI: 0000000000000006
> RBP: 00000000004d29e9 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000077bf80
> R13: 0000000000000000 R14: 000000000077bf80 R15: 00007ffe26483e60
>  </TASK>
> Modules linked in:
> CR2: 0000000000006020
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:can_rcv_filter+0x44/0x4e0 net/can/af_can.c:584
> Code: 00 00 00 e8 3e 86 0f fd 49 8b 9e d8 00 00 00 48 89 df e8 af 81
> 0f fd 44 8b 23 48 8d bd 20 60 00 00 e8 a0 81 0f fd 48 89 2c 24 <8b> 9d
> 20 60 00 00 45 31 ed 31 ff 89 de e8 9a 1c fc fc 85 db 0f 84
> RSP: 0018:ffffc90000003d50 EFLAGS: 00010246
> RAX: ffff88813bc274d8 RBX: ffff8881310c5a10 RCX: ffffffff842b9940
> RDX: 0000000000000522 RSI: 0000000000000000 RDI: 0000000000006020
> RBP: 0000000000000000 R08: 0000000000006023 R09: 0000000000000000
> R10: 0001ffffffffffff R11: 00018881310c5a04 R12: 0000000000000000
> R13: ffff888106fb8880 R14: ffff8881308cba00 R15: 0000000000000000
> FS:  00007fc9368b0700(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000006020 CR3: 0000000132249000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000020000180 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
> ----------------
> Code disassembly (best guess):
>    0: 00 00                add    %al,(%rax)
>    2: 00 e8                add    %ch,%al
>    4: 3e 86 0f              xchg   %cl,%ds:(%rdi)
>    7: fd                    std
>    8: 49 8b 9e d8 00 00 00 mov    0xd8(%r14),%rbx
>    f: 48 89 df              mov    %rbx,%rdi
>   12: e8 af 81 0f fd        callq  0xfd0f81c6
>   17: 44 8b 23              mov    (%rbx),%r12d
>   1a: 48 8d bd 20 60 00 00 lea    0x6020(%rbp),%rdi
>   21: e8 a0 81 0f fd        callq  0xfd0f81c6
>   26: 48 89 2c 24          mov    %rbp,(%rsp)
> * 2a: 8b 9d 20 60 00 00    mov    0x6020(%rbp),%ebx <-- trapping instruction
>   30: 45 31 ed              xor    %r13d,%r13d
>   33: 31 ff                xor    %edi,%edi
>   35: 89 de                mov    %ebx,%esi
>   37: e8 9a 1c fc fc        callq  0xfcfc1cd6
>   3c: 85 db                test   %ebx,%ebx
>   3e: 0f                    .byte 0xf
>   3f: 84                    .byte 0x84
>
> Best,
> Wei