general protection fault in fire_user_return_notifiers

From: syzbot
Date: Mon Oct 21 2019 - 01:25:10 EST

Hello,

syzbot found the following crash on:

HEAD commit: eda57a0e Merge branch 'akpm' (patches from Andrew)
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17310520e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=966954bb171a60e7
dashboard link: https://syzkaller.appspot.com/bug?extid=529818c5c7cdf607bf0e
compiler: clang version 9.0.0 (/home/glider/llvm/clang 80fee25776c2fb61e74c1ecb1a523375c2500b69)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+529818c5c7cdf607bf0e@xxxxxxxxxxxxxxxxxxxxxxxxx

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7781 Comm: syz-executor.2 Not tainted 5.4.0-rc2+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fire_user_return_notifiers+0x90/0x110 kernel/user-return-notifier.c:42
Code: 00 48 8b 1b 48 85 db 74 06 48 83 c3 f8 75 10 e8 96 e2 e3 ff eb 54 0f 1f 40 00 e8 8b e2 e3 ff 48 8d 7b 08 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 74 05 e8 b4 1b 1d 00 4c 8b 73 08 48 89 d8 48 c1 e8
RSP: 0018:ffff888068db7e38 EFLAGS: 00010a02
RAX: 1bd5a00000000020 RBX: dead0000000000f8 RCX: ffff888068dac0c0
RDX: 0000000000000000 RSI: 0023001000000000 RDI: dead000000000100
RBP: ffff888068db7e50 R08: ffffffff8109b34e R09: ffffed100d1b5819
R10: ffffed100d1b5819 R11: 0000000000000000 R12: 0000000000000800
R13: dffffc0000000000 R14: dead000000000100 R15: dffffc0000000000
FS: 00000000024a9940(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000068d86000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
exit_to_usermode_loop arch/x86/entry/common.c:168 [inline]
prepare_exit_to_usermode+0x3fd/0x580 arch/x86/entry/common.c:194
syscall_return_slowpath+0x113/0x4a0 arch/x86/entry/common.c:274
do_syscall_64+0x11f/0x1c0 arch/x86/entry/common.c:300
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457f00
Code: c0 5b 5d c3 66 0f 1f 44 00 00 8b 04 24 48 83 c4 18 5b 5d c3 66 0f 1f 44 00 00 83 3d 51 e8 61 00 00 75 14 b8 23 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 24 d3 fb ff c3 48 83 ec 08 e8 ea 46 00 00
RSP: 002b:00007fff163eec28 EFLAGS: 00000246 ORIG_RAX: 0000000000000023
RAX: 0000000000000000 RBX: 000000000007cbd9 RCX: 0000000000457f00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fff163eec30
RBP: 0000000000000a99 R08: 0000000000000001 R09: 00000000024a9940
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000000d
R13: 00007fff163eec80 R14: 000000000007c8a4 R15: 00007fff163eec90
Modules linked in:
---[ end trace ff1f073ed00222a2 ]---
RIP: 0010:fire_user_return_notifiers+0x90/0x110 kernel/user-return-notifier.c:42
Code: 00 48 8b 1b 48 85 db 74 06 48 83 c3 f8 75 10 e8 96 e2 e3 ff eb 54 0f 1f 40 00 e8 8b e2 e3 ff 48 8d 7b 08 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 74 05 e8 b4 1b 1d 00 4c 8b 73 08 48 89 d8 48 c1 e8
RSP: 0018:ffff888068db7e38 EFLAGS: 00010a02
RAX: 1bd5a00000000020 RBX: dead0000000000f8 RCX: ffff888068dac0c0
RDX: 0000000000000000 RSI: 0023001000000000 RDI: dead000000000100
RBP: ffff888068db7e50 R08: ffffffff8109b34e R09: ffffed100d1b5819
R10: ffffed100d1b5819 R11: 0000000000000000 R12: 0000000000000800
R13: dffffc0000000000 R14: dead000000000100 R15: dffffc0000000000
FS: 00000000024a9940(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000068d86000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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