linux-kernel - Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_sock_ready

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <69731bbd.050a0220.1ad174.0336.GAE@google.com>
Date: Thu, 22 Jan 2026 22:57:01 -0800
From: syzbot <syzbot+9265e754091c2d27ea29@...kaller.appspotmail.com>
To: hdanton@...a.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in
 l2cap_sock_ready_cb (2)

Hello,

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

Oops: general protection fault, probably for non-canonical address 0xdffffc000000004c: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000260-0x0000000000000267]
CPU: 1 UID: 0 PID: 6371 Comm: kworker/u33:6 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: hci0 hci_rx_work
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 0f 1f 40 d6 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 e9 ce 86 08 09 66 66 2e 0f 1f 84 00 00 00
RSP: 0018:ffffc900036c77d8 EFLAGS: 00010282
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff89422bb1 RDI: dffffc000000004c
RBP: 0000000000000260 R08: 0000000000000001 R09: 0000000000000000
R10: ffffc900036c78c8 R11: 00000000000075a9 R12: ffffffff89422bb1
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880d66dc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f01e4fde2f8 CR3: 000000000e392000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __kasan_check_byte+0x13/0x50 mm/kasan/common.c:573
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire kernel/locking/lockdep.c:5842 [inline]
 lock_acquire+0xf5/0x330 kernel/locking/lockdep.c:5825
 lock_sock_nested+0x41/0xf0 net/core/sock.c:3780
 lock_sock include/net/sock.h:1700 [inline]
 l2cap_sock_new_connection_cb+0x4c/0x260 net/bluetooth/l2cap_sock.c:1476
 l2cap_connect_cfm+0x4e2/0x1010 net/bluetooth/l2cap_core.c:7288
 hci_connect_cfm include/net/bluetooth/hci_core.h:2131 [inline]
 hci_remote_features_evt+0x4f4/0x9b0 net/bluetooth/hci_event.c:3729
 hci_event_func net/bluetooth/hci_event.c:7719 [inline]
 hci_event_packet+0xa86/0x11c0 net/bluetooth/hci_event.c:7773
 hci_rx_work+0x451/0xfc0 net/bluetooth/hci_core.c:4076
 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
 process_scheduled_works kernel/workqueue.c:3340 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </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 0f 1f 40 d6 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 e9 ce 86 08 09 66 66 2e 0f 1f 84 00 00 00
RSP: 0018:ffffc900036c77d8 EFLAGS: 00010282
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff89422bb1 RDI: dffffc000000004c
RBP: 0000000000000260 R08: 0000000000000001 R09: 0000000000000000
R10: ffffc900036c78c8 R11: 00000000000075a9 R12: ffffffff89422bb1
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880d66dc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f01e4fde2f8 CR3: 000000003084d000 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:	0f 1f 40 d6          	nopl   -0x2a(%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:	e9 ce 86 08 09       	jmp    0x9088705
  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:         c072629f Merge tag 'v6.19-p4' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10c95f9a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f1fac0919970b671
dashboard link: https://syzkaller.appspot.com/bug?extid=9265e754091c2d27ea29
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16ec813a580000