BUG: unable to handle kernel paging request in br_del_frame

Status: upstream: reported syz repro on 2026/08/12 17:14
Reported-by: syzbot+5c4853fd75ad126b1c29@syzkaller.appspotmail.com
First crash: 4d23h, last: 2h35m

Sample crash report:
device bridge_slave_1 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
device bridge_slave_0 left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
Unable to handle kernel paging request at virtual address fbd5200000000024
KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]
Mem abort info:
  ESR = 0x0000000096000004
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x04: level 0 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000004
  CM = 0, WnR = 0
[fbd5200000000024] address between user and kernel address ranges
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4413 Comm: kworker/u4:5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
Workqueue: netns cleanup_net
pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : __hlist_del include/linux/list.h:884 [inline]
pc : hlist_del_rcu include/linux/rculist.h:513 [inline]
pc : br_del_frame+0xcc/0x158 net/bridge/br_input.c:445
lr : br_del_frame+0x2c/0x158 net/bridge/br_input.c:440
sp : ffff800020e477a0
x29: ffff800020e477a0 x28: 1fffe0001b138600 x27: dfff800000000000
x26: dead000000000122 x25: dfff800000000000 x24: 1fffe0001b551101
x23: 1ffff00002a7384b x22: dfff800000000000 x21: 0000000000000000
x20: ffff80001539c258 x19: dead000000000122 x18: 1fffe00033e7277e
x17: ffff80001537d000 x16: ffff8000082dd248 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe00033e728a8 x12: 0000000000000000
x11: ff00800010b6d980 x10: 0000000000000000 x9 : ffff800010b6d980
x8 : 1bd5a00000000024 x7 : ffff80000836192c x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000006 x1 : ffff80001539c240 x0 : ffff0000d1b24c80
Call trace:
 __hlist_del include/linux/list.h:884 [inline]
 hlist_del_rcu include/linux/rculist.h:513 [inline]
 br_del_frame+0xcc/0x158 net/bridge/br_input.c:445
 mep_delete_implementation+0x268/0x2b4 net/bridge/br_cfm.c:591
 br_cfm_port_del+0x108/0x1bc net/bridge/br_cfm.c:872
 del_nbp+0x154/0x910 net/bridge/br_if.c:347
 br_dev_delete+0x70/0x134 net/bridge/br_if.c:386
 default_device_exit_batch+0x7e4/0xa70 net/core/dev.c:11544
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x650/0xa90 net/core/net_namespace.c:640
 process_one_work+0x7e4/0x13bc kernel/workqueue.c:2292
 worker_thread+0x8cc/0xfe8 kernel/workqueue.c:2439
 kthread+0x254/0x2e0 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
Code: aa1403e0 97d2209e f9400293 d343fe68 (38766908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	aa1403e0 	mov	x0, x20
   4:	97d2209e 	bl	0xffffffffff48827c
   8:	f9400293 	ldr	x19, [x20]
   c:	d343fe68 	lsr	x8, x19, #3
* 10:	38766908 	ldrb	w8, [x8, x22] <-- trapping instruction

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/12 17:13 linux-6.1.y e4f7d8be268e f8d35649 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in br_del_frame
2026/08/17 14:15 linux-6.1.y e4f7d8be268e 905244d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in br_del_frame
* Struck through repros no longer work on HEAD.