syzbot


BUG: unable to handle kernel paging request in mld_clear_delrec

Status: upstream: reported on 2025/07/10 11:40
Reported-by: syzbot+46cd85402c8acc577264@syzkaller.appspotmail.com
First crash: 15d, last: 6h03m
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in mld_clear_delrec net 2 88 7h13m 78d 0/29 upstream: reported on 2025/05/08 01:23

Sample crash report:
Unable to handle kernel paging request at virtual address 00000000ffff0000
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005
  CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000117fe0000
[00000000ffff0000] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4604 Comm: kworker/u4:13 Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: netns cleanup_net
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : mld_clear_delrec+0x37c/0x5f4 net/ipv6/mcast.c:834
lr : mld_clear_delrec+0x360/0x5f4 net/ipv6/mcast.c:834
sp : ffff800020f974f0
x29: ffff800020f974f0 x28: ffff800017a77000 x27: ffff0000f213a800
x26: dfff800000000000 x25: 0000000000000001 x24: ffff800017a77000
x23: 0000000000000001 x22: 00000000ffff0000 x21: ffff800013a8a760
x20: ffff800013a8a740 x19: ffff0000f3d3d000 x18: ffff800011aabce0
x17: 1fffe00033ed9d7e x16: ffff8000082d0ec4 x15: 0000000000000000
x14: 00000000ffff8000 x13: 1ffff00002a160b1 x12: 0000000000ff0100
x11: ff00800010804790 x10: 0000000000000000 x9 : ffff800010804790
x8 : 0000000000000000 x7 : ffff800008355a28 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000006 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
 mld_clear_delrec+0x37c/0x5f4 net/ipv6/mcast.c:834
 ipv6_mc_destroy_dev+0x50/0x508 net/ipv6/mcast.c:2799
 addrconf_ifdown+0x1188/0x15dc net/ipv6/addrconf.c:3942
 addrconf_notify+0x2f4/0xca8 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:455
 call_netdevice_notifiers_info net/core/dev.c:2001 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2039 [inline]
 call_netdevice_notifiers net/core/dev.c:2053 [inline]
 unregister_netdevice_many+0xe2c/0x1740 net/core/dev.c:10978
 ip_tunnel_delete_nets+0x2cc/0x320 net/ipv4/ip_tunnel.c:1171
 ipgre_tap_exit_batch_net+0x30/0x40 net/ipv4/ip_gre.c:1705
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x644/0xa74 net/core/net_namespace.c:640
 process_one_work+0x7f4/0x13a8 kernel/workqueue.c:2292
 worker_thread+0x8c8/0xfbc kernel/workqueue.c:2439
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:849
Code: 387a6908 34000068 aa1603e0 960347cc (f84306d7) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	387a6908 	ldrb	w8, [x8, x26]
   4:	34000068 	cbz	w8, 0x10
   8:	aa1603e0 	mov	x0, x22
   c:	960347cc 	bl	0xfffffffff80d1f3c
* 10:	f84306d7 	ldr	x23, [x22], #48 <-- trapping instruction

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/25 08:25 linux-6.1.y 3594f306da12 fb8f743d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in mld_clear_delrec
2025/07/10 11:39 linux-6.1.y 04d1ccaa9c28 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in mld_clear_delrec
* Struck through repros no longer work on HEAD.