syzbot


BUG: unable to handle kernel paging request in update_vf

Status: upstream: reported on 2025/07/13 20:03
Reported-by: syzbot+27a6ab23ea1c552c640d@syzkaller.appspotmail.com
First crash: 5d04h, last: 2d00h

Sample crash report:
Unable to handle kernel paging request at virtual address dfff800000000012
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
[dfff800000000012] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 5935 Comm: syz.5.399 Not tainted 5.15.187-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : update_vf+0x40/0xca8 net/sched/sch_hfsc.c:754
lr : update_vf+0x38/0xca8 net/sched/sch_hfsc.c:750
sp : ffff800021496c70
x29: ffff800021496cb0 x28: dfff800000000000 x27: dfff800000000000
x26: 0000000000000000 x25: ffff800012d45da8 x24: ffff800012d45da0
x23: 0000000000000000 x22: ffff8000162edce0 x21: 0000000000000000
x20: 0000000000000000 x19: 0000000000000090 x18: 0000000000000201
x17: 0000000000000002 x16: ffff8000082bf708 x15: 00000000ffffffff
x14: 0000000000ff0100 x13: ffffffffffffffff x12: 0000000000080000
x11: 0000000000001654 x10: ffff80002c401000 x9 : ffff80000f95959c
x8 : 0000000000000012 x7 : ffff80000f8d3b08 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002
x2 : 0000000000000008 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 update_vf+0x40/0xca8 net/sched/sch_hfsc.c:754
 hfsc_qlen_notify+0x30/0xb4 net/sched/sch_hfsc.c:1234
 qdisc_tree_reduce_backlog+0x250/0x410 net/sched/sch_api.c:799
 pie_change+0x7c8/0xb5c net/sched/sch_pie.c:202
 pie_init+0x1f0/0x334 net/sched/sch_pie.c:451
 qdisc_create+0x6e4/0xf24 net/sched/sch_api.c:1260
 tc_modify_qdisc+0x8bc/0x1308 net/sched/sch_api.c:-1
 rtnetlink_rcv_msg+0x9d4/0xd04 net/core/rtnetlink.c:5650
 netlink_rcv_skb+0x208/0x3c4 net/netlink/af_netlink.c:2489
 rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:5668
 netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
 netlink_unicast+0x60c/0x89c net/netlink/af_netlink.c:1337
 netlink_sendmsg+0x6e8/0x9cc net/netlink/af_netlink.c:1905
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x61c/0x920 net/socket.c:2436
 ___sys_sendmsg+0x1d0/0x240 net/socket.c:2490
 __sys_sendmsg net/socket.c:2519 [inline]
 __do_sys_sendmsg net/socket.c:2528 [inline]
 __se_sys_sendmsg net/socket.c:2526 [inline]
 __arm64_sys_sendmsg+0x1a8/0x254 net/socket.c:2526
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
Code: f2fbfffc 962c8334 91024293 d343fe68 (387c6908) 
---[ end trace a655bcfc2ec39805 ]---
----------------
Code disassembly (best guess):
   0:	f2fbfffc 	movk	x28, #0xdfff, lsl #48
   4:	962c8334 	bl	0xfffffffff8b20cd4
   8:	91024293 	add	x19, x20, #0x90
   c:	d343fe68 	lsr	x8, x19, #3
* 10:	387c6908 	ldrb	w8, [x8, x28] <-- trapping instruction

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/13 20:02 linux-5.15.y 2f693b607545 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 BUG: unable to handle kernel paging request in update_vf
2025/07/17 00:28 linux-5.15.y 89950c454265 44f8051e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in update_vf
2025/07/16 13:44 linux-5.15.y 89950c454265 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in update_vf
2025/07/15 08:31 linux-5.15.y 89950c454265 03fcfc4b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in update_vf
2025/07/15 08:24 linux-5.15.y 89950c454265 03fcfc4b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in update_vf
2025/07/15 08:23 linux-5.15.y 89950c454265 03fcfc4b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in update_vf
2025/07/14 21:36 linux-5.15.y 89950c454265 d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in update_vf
* Struck through repros no longer work on HEAD.