linux-kernel - Re: [syzbot] [mm?] [bcachefs?] WARNING in lock_list_lru_of

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Message-ID: <67b4c57a.050a0220.14d86d.0009.GAE@google.com>
Date: Tue, 18 Feb 2025 09:38:02 -0800
From: syzbot <syzbot+38a0cbd267eff2d286ff@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, mmpgouride@...il.com, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] [bcachefs?] WARNING in lock_list_lru_of_memcg

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel NULL pointer dereference in qlist_free_all

BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 3f9de067 P4D 3f9de067 PUD 40014067 PMD 0 
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5357 Comm: kworker/0:3 Not tainted 6.14.0-rc3-syzkaller-g2408a807bfc3-dirty #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events nsim_fib_event_work
RIP: 0010:qlink_to_cache mm/kasan/quarantine.c:131 [inline]
RIP: 0010:qlist_free_all+0x69/0x140 mm/kasan/quarantine.c:176
Code: e8 06 48 83 e0 c0 49 8b 4c 05 08 f6 c1 01 0f 85 a8 00 00 00 4c 01 e8 66 90 0f b6 48 33 c1 e1 18 81 f9 00 00 00 f5 48 0f 45 c5 <48> 8b 58 08 4d 8b 34 24 48 63 83 c0 00 00 00 49 29 c4 48 89 df 4c
RSP: 0018:ffffc9000d477568 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000ff000000
RDX: 0000000000000000 RSI: 0000000013ec5780 RDI: 000000001fffffff
RBP: 0000000000000000 R08: ffffffff816eac95 R09: ffffffff82290c0f
R10: dffffc0000000000 R11: fffffbfff28a8d0f R12: ffffffff93ec5780
R13: ffffea0000000000 R14: ffffffff93ec5780 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 00000000365b0000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4115 [inline]
 slab_alloc_node mm/slub.c:4164 [inline]
 __kmalloc_cache_noprof+0x1d9/0x390 mm/slub.c:4320
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 nsim_fib4_rt_create drivers/net/netdevsim/fib.c:280 [inline]
 nsim_fib4_rt_insert drivers/net/netdevsim/fib.c:426 [inline]
 nsim_fib4_event drivers/net/netdevsim/fib.c:464 [inline]
 nsim_fib_event drivers/net/netdevsim/fib.c:884 [inline]
 nsim_fib_event_work+0xe02/0x3f00 drivers/net/netdevsim/fib.c:1493
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xabe/0x18e0 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Modules linked in:
CR2: 0000000000000008
---[ end trace 0000000000000000 ]---
RIP: 0010:qlink_to_cache mm/kasan/quarantine.c:131 [inline]
RIP: 0010:qlist_free_all+0x69/0x140 mm/kasan/quarantine.c:176
Code: e8 06 48 83 e0 c0 49 8b 4c 05 08 f6 c1 01 0f 85 a8 00 00 00 4c 01 e8 66 90 0f b6 48 33 c1 e1 18 81 f9 00 00 00 f5 48 0f 45 c5 <48> 8b 58 08 4d 8b 34 24 48 63 83 c0 00 00 00 49 29 c4 48 89 df 4c
RSP: 0018:ffffc9000d477568 EFLAGS: 00010206
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000ff000000
RDX: 0000000000000000 RSI: 0000000013ec5780 RDI: 000000001fffffff
RBP: 0000000000000000 R08: ffffffff816eac95 R09: ffffffff82290c0f
R10: dffffc0000000000 R11: fffffbfff28a8d0f R12: ffffffff93ec5780
R13: ffffea0000000000 R14: ffffffff93ec5780 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 00000000365b0000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	e8 06 48 83 e0       	call   0xe083480b
   5:	c0 49 8b 4c          	rorb   $0x4c,-0x75(%rcx)
   9:	05 08 f6 c1 01       	add    $0x1c1f608,%eax
   e:	0f 85 a8 00 00 00    	jne    0xbc
  14:	4c 01 e8             	add    %r13,%rax
  17:	66 90                	xchg   %ax,%ax
  19:	0f b6 48 33          	movzbl 0x33(%rax),%ecx
  1d:	c1 e1 18             	shl    $0x18,%ecx
  20:	81 f9 00 00 00 f5    	cmp    $0xf5000000,%ecx
  26:	48 0f 45 c5          	cmovne %rbp,%rax
* 2a:	48 8b 58 08          	mov    0x8(%rax),%rbx <-- trapping instruction
  2e:	4d 8b 34 24          	mov    (%r12),%r14
  32:	48 63 83 c0 00 00 00 	movslq 0xc0(%rbx),%rax
  39:	49 29 c4             	sub    %rax,%r12
  3c:	48 89 df             	mov    %rbx,%rdi
  3f:	4c                   	rex.WR


Tested on:

commit:         2408a807 Merge tag 'vfs-6.14-rc4.fixes' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=113477df980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b7bde34acd8f53b1
dashboard link: https://syzkaller.appspot.com/bug?extid=38a0cbd267eff2d286ff
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=114603a4580000