Re: [syzbot] general protection fault in sock_from_file

From: Dmitry Vyukov
Date: Mon Aug 30 2021 - 15:22:58 EST

On Mon, 30 Aug 2021 at 21:19, syzbot
<syzbot+f9704d1878e290eddf73@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 93717cde744f Add linux-next specific files for 20210830
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=15b851fe300000
> kernel config: https://syzkaller.appspot.com/x/.config?x=c643ef5289990dd1
> dashboard link: https://syzkaller.appspot.com/bug?extid=f9704d1878e290eddf73
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f9704d1878e290eddf73@xxxxxxxxxxxxxxxxxxxxxxxxx

+io_uring maintainers as this looks io_uring-related

> general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
> CPU: 1 PID: 6072 Comm: syz-executor.0 Not tainted 5.14.0-next-20210830-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:sock_from_file+0x20/0x90 net/socket.c:505
> Code: f5 ff ff ff c3 0f 1f 44 00 00 41 54 53 48 89 fb e8 85 e9 62 fa 48 8d 7b 28 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 4f 45 31 e4 48 81 7b 28 80 f1 8a 8a 74 0c e8 58 e9
> RSP: 0018:ffffc9000a2df8e8 EFLAGS: 00010206
> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90002f91000
> RDX: 0000000000000005 RSI: ffffffff8713203b RDI: 0000000000000028
> RBP: ffff8880983c2c80 R08: ffffffff899aee40 R09: ffffffff81e21978
> R10: 0000000000000027 R11: 0000000000000009 R12: dffffc0000000000
> R13: 1ffff11013078599 R14: 0000000000000003 R15: ffff8880983c2c80
> FS: 00007fe7b0454700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00005591dffa5180 CR3: 00000000974cb000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> io_sendmsg+0x98/0x640 fs/io_uring.c:4681
> io_issue_sqe+0x14de/0x6ba0 fs/io_uring.c:6578
> __io_queue_sqe+0x90/0xb50 fs/io_uring.c:6864
> io_req_task_submit+0xbf/0x1b0 fs/io_uring.c:2218
> tctx_task_work+0x166/0x610 fs/io_uring.c:2143
> task_work_run+0xdd/0x1a0 kernel/task_work.c:164
> tracehook_notify_signal include/linux/tracehook.h:212 [inline]
> handle_signal_work kernel/entry/common.c:146 [inline]
> exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
> exit_to_user_mode_prepare+0x256/0x290 kernel/entry/common.c:209
> __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
> syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
> do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x4665f9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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:00007fe7b0454188 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
> RAX: 0000000000001000 RBX: 000000000056bf80 RCX: 00000000004665f9
> RDX: 0000000000000000 RSI: 000000000000688c RDI: 0000000000000003
> RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
> R13: 00007fffeee6585f R14: 00007fe7b0454300 R15: 0000000000022000
> Modules linked in:
> ---[ end trace 6f9e359dd487b8fa ]---
> RIP: 0010:sock_from_file+0x20/0x90 net/socket.c:505
> Code: f5 ff ff ff c3 0f 1f 44 00 00 41 54 53 48 89 fb e8 85 e9 62 fa 48 8d 7b 28 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 4f 45 31 e4 48 81 7b 28 80 f1 8a 8a 74 0c e8 58 e9
> RSP: 0018:ffffc9000a2df8e8 EFLAGS: 00010206
> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90002f91000
> RDX: 0000000000000005 RSI: ffffffff8713203b RDI: 0000000000000028
> RBP: ffff8880983c2c80 R08: ffffffff899aee40 R09: ffffffff81e21978
> R10: 0000000000000027 R11: 0000000000000009 R12: dffffc0000000000
> R13: 1ffff11013078599 R14: 0000000000000003 R15: ffff8880983c2c80
> FS: 00007fe7b0454700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fb81002c710 CR3: 00000000974cb000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess), 3 bytes skipped:
> 0: ff c3 inc %ebx
> 2: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> 7: 41 54 push %r12
> 9: 53 push %rbx
> a: 48 89 fb mov %rdi,%rbx
> d: e8 85 e9 62 fa callq 0xfa62e997
> 12: 48 8d 7b 28 lea 0x28(%rbx),%rdi
> 16: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
> 1d: fc ff df
> 20: 48 89 fa mov %rdi,%rdx
> 23: 48 c1 ea 03 shr $0x3,%rdx
> * 27: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
> 2b: 75 4f jne 0x7c
> 2d: 45 31 e4 xor %r12d,%r12d
> 30: 48 81 7b 28 80 f1 8a cmpq $0xffffffff8a8af180,0x28(%rbx)
> 37: 8a
> 38: 74 0c je 0x46
> 3a: e8 .byte 0xe8
> 3b: 58 pop %rax
> 3c: e9 .byte 0xe9
>
>
> ---
> 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.
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/00000000000011360d05cacbb622%40google.com.