linux-kernel - Re: [syzbot] [serial?] possible deadlock in console_flush

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Date: Tue, 05 Mar 2024 07:21:02 -0800
From: syzbot <syzbot+f78380e4eae53c64125c@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, penguin-kernel@...ove.sakura.ne.jp, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [serial?] possible deadlock in console_flush_all (2)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in locks_remove_posix

general protection fault, probably for non-canonical address 0xdffffc0020008013: 0000 [#1] PREEMPT SMP KASAN
KASAN: probably user-memory-access in range [0x0000000100040098-0x000000010004009f]
CPU: 1 PID: 5487 Comm: dhcpcd-run-hook Not tainted 6.8.0-rc6-syzkaller-g8f50d5c42355-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
RIP: 0010:list_empty include/linux/list.h:373 [inline]
RIP: 0010:locks_remove_posix+0xff/0x440 fs/locks.c:2554
Code: 4d 8b be 20 02 00 00 4d 85 ff 0f 84 9f 01 00 00 e8 16 ea 7b ff 49 8d 47 50 48 ba 00 00 00 00 00 fc ff df 48 89 c1 48 c1 e9 03 <80> 3c 11 00 0f 85 09 03 00 00 49 8b 57 50 48 39 d0 0f 84 6e 01 00
RSP: 0018:ffffc9000388f978 EFLAGS: 00010202
RAX: 0000000100040098 RBX: ffff888019b36500 RCX: 0000000020008013
RDX: dffffc0000000000 RSI: ffffffff820b2e1a RDI: ffff888076090730
RBP: 1ffff92000711f30 R08: 0000000000000003 R09: 0000000000004000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc9000388f9b0
R13: ffff88802a7e0b40 R14: ffff888076090510 R15: 0000000100040048
FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000100040340 CR3: 00000000183e4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 filp_flush+0x11b/0x1a0 fs/open.c:1518
 filp_close+0x1c/0x30 fs/open.c:1527
 close_files fs/file.c:432 [inline]
 put_files_struct fs/file.c:447 [inline]
 put_files_struct+0x1df/0x360 fs/file.c:444
 exit_files+0x82/0xb0 fs/file.c:464
 do_exit+0xa56/0x2ad0 kernel/exit.c:866
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1020
 get_signal+0x23b5/0x2790 kernel/signal.c:2893
 arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:105 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 irqentry_exit_to_user_mode+0x13c/0x280 kernel/entry/common.c:225
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0033:0x7fbec7157428
Code: Unable to access opcode bytes at 0x7fbec71573fe.
RSP: 002b:00007fff8928a8a0 EFLAGS: 00010246
RAX: 0000000100040048 RBX: 0000555b854932c0 RCX: 00007fbec7205098
RDX: 0000000000000000 RSI: 0000555b85495d30 RDI: 0000555b85494930
RBP: 0000555b85494930 R08: 0000000000000000 R09: 0000000000000000
R10: 00007fbec7205088 R11: 0000000000000246 R12: 0000000000000000
R13: 0000555b85495d30 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:list_empty include/linux/list.h:373 [inline]
RIP: 0010:locks_remove_posix+0xff/0x440 fs/locks.c:2554
Code: 4d 8b be 20 02 00 00 4d 85 ff 0f 84 9f 01 00 00 e8 16 ea 7b ff 49 8d 47 50 48 ba 00 00 00 00 00 fc ff df 48 89 c1 48 c1 e9 03 <80> 3c 11 00 0f 85 09 03 00 00 49 8b 57 50 48 39 d0 0f 84 6e 01 00
RSP: 0018:ffffc9000388f978 EFLAGS: 00010202
RAX: 0000000100040098 RBX: ffff888019b36500 RCX: 0000000020008013
RDX: dffffc0000000000 RSI: ffffffff820b2e1a RDI: ffff888076090730
RBP: 1ffff92000711f30 R08: 0000000000000003 R09: 0000000000004000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc9000388f9b0
R13: ffff88802a7e0b40 R14: ffff888076090510 R15: 0000000100040048
FS:  0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000100040340 CR3: 00000000183e4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	4d 8b be 20 02 00 00 	mov    0x220(%r14),%r15
   7:	4d 85 ff             	test   %r15,%r15
   a:	0f 84 9f 01 00 00    	je     0x1af
  10:	e8 16 ea 7b ff       	call   0xff7bea2b
  15:	49 8d 47 50          	lea    0x50(%r15),%rax
  19:	48 ba 00 00 00 00 00 	movabs $0xdffffc0000000000,%rdx
  20:	fc ff df
  23:	48 89 c1             	mov    %rax,%rcx
  26:	48 c1 e9 03          	shr    $0x3,%rcx
* 2a:	80 3c 11 00          	cmpb   $0x0,(%rcx,%rdx,1) <-- trapping instruction
  2e:	0f 85 09 03 00 00    	jne    0x33d
  34:	49 8b 57 50          	mov    0x50(%r15),%rdx
  38:	48 39 d0             	cmp    %rdx,%rax
  3b:	0f                   	.byte 0xf
  3c:	84 6e 01             	test   %ch,0x1(%rsi)


Tested on:

commit:         8f50d5c4 Merge branch 'Allow struct_ops maps with a la..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15c2d486180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7e085fc648b10d1e
dashboard link: https://syzkaller.appspot.com/bug?extid=f78380e4eae53c64125c
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=121c92fe180000