Re: WARNING in wp_page_copy

[Daniel Borkmann]

On Sat, Dec 14, 2019 at 08:20:07AM -0800, syzbot wrote:
> syzbot has found a reproducer for the following crash on:
> 
> HEAD commit:    1d1997db Revert "nfp: abm: fix memory leak in nfp_abm_u32_..
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1029f851e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cef1fd5032faee91
> dashboard link: https://syzkaller.appspot.com/bug?extid=9301f2f33873407d5b33
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=119d9fb1e00000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+9301f2f33873407d5b33@xxxxxxxxxxxxxxxxxxxxxxxxx

Bjorn / Magnus, given xsk below, PTAL, thanks!

> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 9104 at mm/memory.c:2229 cow_user_page mm/memory.c:2229
> [inline]
> WARNING: CPU: 0 PID: 9104 at mm/memory.c:2229 wp_page_copy+0x10b7/0x1560
> mm/memory.c:2414
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 9104 Comm: syz-executor.0 Not tainted 5.5.0-rc1-syzkaller #0
> 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+0x197/0x210 lib/dump_stack.c:118
>  panic+0x2e3/0x75c kernel/panic.c:221
>  __warn.cold+0x2f/0x3e kernel/panic.c:582
>  report_bug+0x289/0x300 lib/bug.c:195
>  fixup_bug arch/x86/kernel/traps.c:174 [inline]
>  fixup_bug arch/x86/kernel/traps.c:169 [inline]
>  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
>  do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
>  invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
> RIP: 0010:cow_user_page mm/memory.c:2229 [inline]
> RIP: 0010:wp_page_copy+0x10b7/0x1560 mm/memory.c:2414
> Code: 4c 89 f7 ba 00 10 00 00 48 81 e6 00 f0 ff ff e8 0f e6 22 06 31 ff 41
> 89 c7 89 c6 e8 23 03 d3 ff 45 85 ff 74 0f e8 99 01 d3 ff <0f> 0b 4c 89 f7 e8
> 3f d8 22 06 e8 8a 01 d3 ff 65 4c 8b 34 25 c0 1e
> RSP: 0018:ffffc90002267668 EFLAGS: 00010293
> RAX: ffff8880a04c6140 RBX: ffffc90002267918 RCX: ffffffff81a22a0d
> RDX: 0000000000000000 RSI: ffffffff81a22a17 RDI: 0000000000000005
> RBP: ffffc900022677a8 R08: ffff8880a04c6140 R09: 0000000000000000
> R10: ffffed101125cfff R11: ffff8880892e7fff R12: ffff88809e403108
> R13: ffffea000224b9c0 R14: ffff8880892e7000 R15: 0000000000001000
>  do_wp_page+0x543/0x1540 mm/memory.c:2724
>  handle_pte_fault mm/memory.c:3961 [inline]
>  __handle_mm_fault+0x327b/0x3da0 mm/memory.c:4075
>  handle_mm_fault+0x3b2/0xa50 mm/memory.c:4112
>  do_user_addr_fault arch/x86/mm/fault.c:1441 [inline]
>  __do_page_fault+0x536/0xd80 arch/x86/mm/fault.c:1506
>  do_page_fault+0x38/0x590 arch/x86/mm/fault.c:1530
>  page_fault+0x39/0x40 arch/x86/entry/entry_64.S:1203
> RIP: 0010:copy_user_generic_unrolled+0x89/0xc0
> arch/x86/lib/copy_user_64.S:91
> Code: 38 4c 89 47 20 4c 89 4f 28 4c 89 57 30 4c 89 5f 38 48 8d 76 40 48 8d
> 7f 40 ff c9 75 b6 89 d1 83 e2 07 c1 e9 03 74 12 4c 8b 06 <4c> 89 07 48 8d 76
> 08 48 8d 7f 08 ff c9 75 ee 21 d2 74 10 89 d1 8a
> RSP: 0018:ffffc90002267bb8 EFLAGS: 00010206
> RAX: 0000000000000001 RBX: 0000000000000018 RCX: 0000000000000003
> RDX: 0000000000000000 RSI: ffffc90002267c58 RDI: 0000000020001300
> RBP: ffffc90002267bf0 R08: 0000000000000000 R09: fffff5200044cf8e
> R10: fffff5200044cf8d R11: ffffc90002267c6f R12: 0000000020001300
> R13: ffffc90002267c58 R14: 0000000020001318 R15: 00007ffffffff000
>  copy_to_user include/linux/uaccess.h:152 [inline]
>  xsk_getsockopt+0x575/0x6c0 net/xdp/xsk.c:898
>  __sys_getsockopt+0x16d/0x310 net/socket.c:2174
>  __do_sys_getsockopt net/socket.c:2189 [inline]
>  __se_sys_getsockopt net/socket.c:2186 [inline]
>  __x64_sys_getsockopt+0xbe/0x150 net/socket.c:2186
>  do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x45a909
> Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f0ec9e9ec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 000000000045a909
> RDX: 0000000000000007 RSI: 000000000000011b RDI: 000000000000000a
> RBP: 000000000075bf20 R08: 0000000020000100 R09: 0000000000000000
> R10: 0000000020001300 R11: 0000000000000246 R12: 00007f0ec9e9f6d4
> R13: 00000000004c1ab5 R14: 00000000004d5f60 R15: 00000000ffffffff
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>