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KASAN: use-after-free Read in l2cap_unregister_user

Status: upstream: reported C repro on 2024/11/07 17:33
Reported-by: syzbot+51b9f0aeb761754e57b8@syzkaller.appspotmail.com
First crash: 529d, last: 2d12h
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 KASAN: use-after-free Read in l2cap_unregister_user origin:upstream 19 C 120 4d21h 516d 0/3 upstream: reported C repro on 2024/11/20 17:00
upstream KASAN: slab-use-after-free Read in l2cap_unregister_user bluetooth 22 C done 46119 5h57m 535d 27/29 upstream: reported C repro on 2024/11/01 18:29
linux-6.6 KASAN: slab-use-after-free Read in l2cap_unregister_user origin:upstream missing-backport 19 syz error 89 35d 305d 0/2 upstream: reported syz repro on 2025/06/19 23:39

Sample crash report:
Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 5271 Comm: syz.3.252 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : l2cap_unregister_user+0x34/0x18c net/bluetooth/l2cap_core.c:1893
lr : l2cap_unregister_user+0x30/0x18c net/bluetooth/l2cap_core.c:1892
sp : ffff8000241b77b0
x29: ffff8000241b77b0 x28: ffff0000c701b780 x27: 00000000000089f0
x26: dfff800000000000 x25: dfff800000000000 x24: ffff8000241b7840
x23: dfff800000000000 x22: dfff800000000000 x21: 0000000000000000
x20: 0000000000000000 x19: ffff0000dd860090 x18: ffff800011b9bf60
x17: 1fffe00033eaa57e x16: ffff8000082d92bc x15: ffff80001521d000
x14: 0000000000000001 x13: 1fffe00033eacc30 x12: 0000000000ff0100
x11: ff00800010c97964 x10: 0000000000000000 x9 : ffff800010c97964
x8 : 0000000000000000 x7 : ffff800008257984 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff8000241b73a0 x1 : ffff0000dd860090 x0 : 0000000000000000
Call trace:
 l2cap_unregister_user+0x34/0x18c net/bluetooth/l2cap_core.c:1893
 hidp_connection_del+0xb0/0x14c net/bluetooth/hidp/core.c:1422
 do_hidp_sock_ioctl net/bluetooth/hidp/sock.c:97 [inline]
 hidp_sock_ioctl+0x60c/0xa70 net/bluetooth/hidp/sock.c:128
 sock_do_ioctl+0x100/0x258 net/socket.c:1201
 sock_ioctl+0x238/0x824 net/socket.c:1320
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa0003f4 f2fbfff7 97cd7691 d343fe88 (38776908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	aa0003f4 	mov	x20, x0
   4:	f2fbfff7 	movk	x23, #0xdfff, lsl #48
   8:	97cd7691 	bl	0xffffffffff35da4c
   c:	d343fe88 	lsr	x8, x20, #3
* 10:	38776908 	ldrb	w8, [x8, x23] <-- trapping instruction

Crashes (163):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/19 02:03 linux-6.1.y 7c87defbd336 303e2802 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in l2cap_unregister_user
2026/01/07 16:54 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2026/01/01 05:58 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/24 09:45 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/23 11:33 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/20 12:44 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/16 05:32 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/10 16:10 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/09 09:59 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/09 06:03 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/05 03:25 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/04 17:37 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/12/02 09:02 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/11/26 23:44 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2025/11/05 09:10 linux-6.1.y f6e38ae624cf a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Read in l2cap_unregister_user
2026/03/10 04:05 linux-6.1.y f2ddafa93a25 6972f302 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/03/09 15:49 linux-6.1.y f2ddafa93a25 176bead5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/03/01 04:36 linux-6.1.y 779f9571ac3e 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/02/25 13:34 linux-6.1.y 779f9571ac3e 94a9671e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/02/11 17:56 linux-6.1.y 8ce36b2849ef 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/01/22 13:20 linux-6.1.y cd9b81672742 a16aed1d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/01/19 07:41 linux-6.1.y cd9b81672742 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/01/16 17:11 linux-6.1.y bec0e10ee67e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/01/08 14:25 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/01/06 16:08 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/01/04 19:41 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/01/03 15:01 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/01/03 02:30 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/30 08:41 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/23 17:44 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/23 00:49 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/19 11:32 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/18 11:55 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/14 18:28 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/08 03:33 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/02 23:41 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/12/01 01:01 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/11/29 23:19 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/11/27 22:16 linux-6.1.y f6e38ae624cf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/11/24 08:44 linux-6.1.y f6e38ae624cf 4fb8ef37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/11/13 17:49 linux-6.1.y f6e38ae624cf 07e030de .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/11/12 05:10 linux-6.1.y f6e38ae624cf 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/11/07 13:01 linux-6.1.y f6e38ae624cf 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2025/11/05 20:59 linux-6.1.y f6e38ae624cf a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2024/11/07 17:32 linux-6.1.y 7c15117f9468 867e44df .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in l2cap_unregister_user
2026/04/19 01:16 linux-6.1.y 7c87defbd336 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in l2cap_unregister_user
* Struck through repros no longer work on HEAD.