Re: [syzbot] [io-uring?] KASAN: slab-use-after-free Read in io_waitid_wait

[syzbot <syzbot+b9e83021d9c642a33d8c@syzkaller.appspotmail.com>]

Hello,

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

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 3 UID: 0 PID: 6397 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:kasan_byte_accessible+0x15/0x30 mm/kasan/generic.c:210
Code: 00 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 48 b8 00 00 00 00 00 fc ff df 48 c1 ef 03 48 01 c7 <0f> b6 07 3c 07 0f 96 c0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00
RSP: 0018:ffffc900027579b0 EFLAGS: 00010086
RAX: dffffc0000000000 RBX: 0000000000000018 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8b54cf9a RDI: dffffc0000000003
RBP: 0000000000000018 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff905ff0d7 R11: 0000000000000000 R12: ffffffff8b54cf9a
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fe7bc5c86c0(0000) GS:ffff8880d7161000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe7bb9e5fac CR3: 00000000504de000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __kasan_check_byte+0x13/0x50 mm/kasan/common.c:579
 kasan_check_byte include/linux/kasan.h:401 [inline]
 lock_acquire kernel/locking/lockdep.c:5842 [inline]
 lock_acquire+0xfc/0x350 kernel/locking/lockdep.c:5825
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
 add_wait_queue+0x45/0x230 kernel/sched/wait.c:23
 io_waitid_cb+0x1c3/0x2b0 io_uring/waitid.c:219
 io_handle_tw_list+0x486/0x500 io_uring/io_uring.c:1151
 tctx_task_work_run+0xac/0x380 io_uring/io_uring.c:1216
 tctx_task_work+0x7a/0xd0 io_uring/io_uring.c:1234
 task_work_run+0x150/0x240 kernel/task_work.c:227
 get_signal+0x1d0/0x26d0 kernel/signal.c:2807
 arch_do_signal_or_restart+0x8f/0x7c0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x85/0x130 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x419/0x4e0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe7bb78eec9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe7bc5c80e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 00007fe7bb9e5fa8 RCX: 00007fe7bb78eec9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fe7bb9e5fa8
RBP: 00007fe7bb9e5fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe7bb9e6038 R14: 00007ffcd14563d0 R15: 00007ffcd14564b8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kasan_byte_accessible+0x15/0x30 mm/kasan/generic.c:210
Code: 00 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 48 b8 00 00 00 00 00 fc ff df 48 c1 ef 03 48 01 c7 <0f> b6 07 3c 07 0f 96 c0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00
RSP: 0018:ffffc900027579b0 EFLAGS: 00010086
RAX: dffffc0000000000 RBX: 0000000000000018 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8b54cf9a RDI: dffffc0000000003
RBP: 0000000000000018 R08: 0000000000000001 R09: 0000000000000000
R10: ffffffff905ff0d7 R11: 0000000000000000 R12: ffffffff8b54cf9a
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007fe7bc5c86c0(0000) GS:ffff8880d7161000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe7bb9e5fac CR3: 00000000504de000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	0f 1f 00             	nopl   (%rax)
   5:	90                   	nop
   6:	90                   	nop
   7:	90                   	nop
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	66 0f 1f 00          	nopw   (%rax)
  19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  20:	fc ff df
  23:	48 c1 ef 03          	shr    $0x3,%rdi
  27:	48 01 c7             	add    %rax,%rdi
* 2a:	0f b6 07             	movzbl (%rdi),%eax <-- trapping instruction
  2d:	3c 07                	cmp    $0x7,%al
  2f:	0f 96 c0             	setbe  %al
  32:	c3                   	ret
  33:	cc                   	int3
  34:	cc                   	int3
  35:	cc                   	int3
  36:	cc                   	int3
  37:	66                   	data16
  38:	66                   	data16
  39:	2e                   	cs
  3a:	0f                   	.byte 0xf
  3b:	1f                   	(bad)
  3c:	84 00                	test   %al,(%rax)


Tested on:

commit:         299d12f3 io_uring/waitid: use io_waitid_remove_wq() co..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux.git syztest
console output: https://syzkaller.appspot.com/x/log.txt?x=12de0dcd980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6da9233e22696ba7
dashboard link: https://syzkaller.appspot.com/bug?extid=b9e83021d9c642a33d8c
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.