linux-kernel - Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_send

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Message-ID: <67874d41.050a0220.20d369.0006.GAE@google.com>
Date: Tue, 14 Jan 2025 21:53:05 -0800
From: syzbot <syzbot+31c2f641b850a348a734@...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_send_cmd

Hello,

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

Bluetooth: Wrong link type (-22)
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 1 UID: 0 PID: 8192 Comm: kworker/u9:7 Not tainted 6.13.0-rc7-syzkaller-g619f0b6fad52-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: hci5 hci_rx_work
RIP: 0010:hci_send_acl+0x3e/0xd00 net/bluetooth/hci_core.c:3232
Code: 00 89 54 24 04 49 89 f5 48 89 fb 49 bf 00 00 00 00 00 fc ff df e8 a2 93 e6 f6 48 89 5c 24 18 4c 8d 73 18 4c 89 f3 48 c1 eb 03 <42> 80 3c 3b 00 74 08 4c 89 f7 e8 c3 fd 4c f7 bd f8 0f 00 00 49 03
RSP: 0018:ffffc900057e72b8 EFLAGS: 00010206
RAX: ffffffff8ab8eece RBX: 0000000000000003 RCX: ffff8880304dbc00
RDX: 0000000000000000 RSI: ffff8880578f5c80 RDI: 0000000000000000
RBP: ffffc900057e7a98 R08: ffffffff8ac38d24 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100dbd7003 R12: ffff88802d5c0f4b
R13: ffff8880578f5c80 R14: 0000000000000018 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c005688000 CR3: 0000000032a00000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 l2cap_sig_send_rej net/bluetooth/l2cap_core.c:5508 [inline]
 l2cap_sig_channel net/bluetooth/l2cap_core.c:5544 [inline]
 l2cap_recv_frame+0x221f/0x10db0 net/bluetooth/l2cap_core.c:6823
 l2cap_recv_acldata+0x51f/0x1530 net/bluetooth/l2cap_core.c:7518
 hci_acldata_packet net/bluetooth/hci_core.c:3797 [inline]
 hci_rx_work+0x508/0xdb0 net/bluetooth/hci_core.c:4040
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:hci_send_acl+0x3e/0xd00 net/bluetooth/hci_core.c:3232
Code: 00 89 54 24 04 49 89 f5 48 89 fb 49 bf 00 00 00 00 00 fc ff df e8 a2 93 e6 f6 48 89 5c 24 18 4c 8d 73 18 4c 89 f3 48 c1 eb 03 <42> 80 3c 3b 00 74 08 4c 89 f7 e8 c3 fd 4c f7 bd f8 0f 00 00 49 03
RSP: 0018:ffffc900057e72b8 EFLAGS: 00010206
RAX: ffffffff8ab8eece RBX: 0000000000000003 RCX: ffff8880304dbc00
RDX: 0000000000000000 RSI: ffff8880578f5c80 RDI: 0000000000000000
RBP: ffffc900057e7a98 R08: ffffffff8ac38d24 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100dbd7003 R12: ffff88802d5c0f4b
R13: ffff8880578f5c80 R14: 0000000000000018 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c005688000 CR3: 000000000e736000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	00 89 54 24 04 49    	add    %cl,0x49042454(%rcx)
   6:	89 f5                	mov    %esi,%ebp
   8:	48 89 fb             	mov    %rdi,%rbx
   b:	49 bf 00 00 00 00 00 	movabs $0xdffffc0000000000,%r15
  12:	fc ff df
  15:	e8 a2 93 e6 f6       	call   0xf6e693bc
  1a:	48 89 5c 24 18       	mov    %rbx,0x18(%rsp)
  1f:	4c 8d 73 18          	lea    0x18(%rbx),%r14
  23:	4c 89 f3             	mov    %r14,%rbx
  26:	48 c1 eb 03          	shr    $0x3,%rbx
* 2a:	42 80 3c 3b 00       	cmpb   $0x0,(%rbx,%r15,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 f7             	mov    %r14,%rdi
  34:	e8 c3 fd 4c f7       	call   0xf74cfdfc
  39:	bd f8 0f 00 00       	mov    $0xff8,%ebp
  3e:	49                   	rex.WB
  3f:	03                   	.byte 0x3


Tested on:

commit:         619f0b6f Merge tag 'seccomp-v6.13-rc8' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=145ebcb0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=aadf89e2f6db86cc
dashboard link: https://syzkaller.appspot.com/bug?extid=31c2f641b850a348a734
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1276bcb0580000