syzbot


general protection fault in qfq_deactivate_class

Status: upstream: reported C repro on 2025/07/10 18:58
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+268bdb68817bd29484c2@syzkaller.appspotmail.com
First crash: 28d, last: 27d
Bug presence (2)
Date Name Commit Repro Result
2025/07/11 linux-5.15.y (ToT) 2f693b607545 C [report] BUG: unable to handle kernel paging request in qfq_deactivate_class
2025/07/11 upstream (ToT) bc9ff192a6c9 C Didn't crash
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 general protection fault in qfq_deactivate_class 2 1 1843d 1843d 0/1 auto-closed as invalid on 2020/11/18 22:39

Sample crash report:
Unable to handle kernel paging request at virtual address dfff80000000000d
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
[dfff80000000000d] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4164 Comm: syz.0.16 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 : qfq_deactivate_class+0x40/0xf5c net/sched/sch_qfq.c:354
lr : qfq_deactivate_class+0x38/0xf5c net/sched/sch_qfq.c:353
sp : ffff80001fc16c80
x29: ffff80001fc16cc0 x28: 1ffff000025a9424 x27: ffff0000ceb9c2c0
x26: dfff800000000000 x25: ffff800012d4a128 x24: ffff800012d4a120
x23: 0000000000000000 x22: ffff8000162edce0 x21: ffff0000ceb9c000
x20: 0000000000000000 x19: 0000000000000000 x18: 0000000000000201
x17: 0000000000000000 x16: ffff8000082bf708 x15: 00000000ffffffff
x14: 0000000000ff0100 x13: ffffffffffffffff x12: 0000000000ff0100
x11: 0000000000000201 x10: 0000000000000000 x9 : ffff80000f9a82f0
x8 : 000000000000000d x7 : ffff80000f8d3b08 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000002
x2 : 0000000000000008 x1 : 0000000000000000 x0 : 0000000000000068
Call trace:
 qfq_deactivate_class+0x40/0xf5c net/sched/sch_qfq.c:354
 qfq_qlen_notify+0x28/0x38 net/sched/sch_qfq.c:1431
 qdisc_tree_reduce_backlog+0x250/0x410 net/sched/sch_api.c:799
 codel_change+0x70c/0x9f8 net/sched/sch_codel.c:183
 codel_init+0x14c/0x2f0 net/sched/sch_codel.c:202
 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: f2fbfffa 962b47df 9101a280 d343fc08 (387a6908) 
---[ end trace 00367777c04a9909 ]---
----------------
Code disassembly (best guess):
   0:	f2fbfffa 	movk	x26, #0xdfff, lsl #48
   4:	962b47df 	bl	0xfffffffff8ad1f80
   8:	9101a280 	add	x0, x20, #0x68
   c:	d343fc08 	lsr	x8, x0, #3
* 10:	387a6908 	ldrb	w8, [x8, x26] <-- trapping instruction

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/11 01:45 linux-5.15.y 2f693b607545 3cda49cf .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 BUG: unable to handle kernel paging request in qfq_deactivate_class
2025/07/10 18:58 linux-5.15.y 2f693b607545 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in qfq_deactivate_class
2025/07/10 22:19 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 qfq_deactivate_class
2025/07/10 21:48 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 qfq_deactivate_class
2025/07/10 19:20 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 qfq_deactivate_class
2025/07/10 19:19 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 qfq_deactivate_class
* Struck through repros no longer work on HEAD.