syzbot


general protection fault in hfsc_qlen_notify

Status: upstream: reported on 2025/07/14 14:50
Reported-by: syzbot+34fa3303360b3b48eca3@syzkaller.appspotmail.com
First crash: 11d, last: 9d19h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 general protection fault in hfsc_qlen_notify 2 4 8d12h 15d 0/3 upstream: reported on 2025/07/10 21:19
upstream general protection fault in hfsc_qlen_notify net 10 C 161 8d18h 22d 27/29 upstream: reported C repro on 2025/07/03 08:17

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc000000005d: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000002e8-0x00000000000002ef]
CPU: 0 PID: 7659 Comm: syz.3.551 Not tainted 6.6.98-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:hfsc_qlen_notify+0x2e/0x160 net/sched/sch_hfsc.c:1237
Code: 55 41 57 41 56 41 55 41 54 53 48 89 f3 49 bc 00 00 00 00 00 fc ff df e8 d0 be f3 f8 4c 8d b3 ec 02 00 00 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 e3 00 00 00 41 8b 2e 31 ff 89 ee e8 59
RSP: 0018:ffffc90004d06dd0 EFLAGS: 00010203
RAX: 000000000000005d RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000d6ac000 RSI: 0000000000000b2f RDI: 0000000000000b30
RBP: dffffc0000000000 R08: ffff888026dc1e00 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: dffffc0000000000
R13: ffff88805ba13000 R14: 00000000000002ec R15: ffff88805ba13000
FS:  00007f8c0504f6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c0504ef98 CR3: 000000005aa85000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 qdisc_tree_reduce_backlog+0x28b/0x470 net/sched/sch_api.c:810
 hhf_change+0x817/0xd30 net/sched/sch_hhf.c:567
 hhf_init+0x219/0x940 net/sched/sch_hhf.c:593
 qdisc_create+0x8eb/0x1050 net/sched/sch_api.c:1322
 tc_modify_qdisc+0xb13/0x1be0 net/sched/sch_api.c:-1
 rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6475
 netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2537
 netlink_unicast_kernel net/netlink/af_netlink.c:1323 [inline]
 netlink_unicast+0x750/0x8c0 net/netlink/af_netlink.c:1349
 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x5bf/0x950 net/socket.c:2595
 ___sys_sendmsg+0x220/0x290 net/socket.c:2649
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2687 [inline]
 __se_sys_sendmsg+0x1a5/0x270 net/socket.c:2685
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f8c0418e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8c0504f038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8c043b6080 RCX: 00007f8c0418e929
RDX: 0000000000004000 RSI: 0000200000000280 RDI: 0000000000000003
RBP: 00007f8c04210b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f8c043b6080 R15: 00007ffe2d9d7478
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:hfsc_qlen_notify+0x2e/0x160 net/sched/sch_hfsc.c:1237
Code: 55 41 57 41 56 41 55 41 54 53 48 89 f3 49 bc 00 00 00 00 00 fc ff df e8 d0 be f3 f8 4c 8d b3 ec 02 00 00 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 e3 00 00 00 41 8b 2e 31 ff 89 ee e8 59
RSP: 0018:ffffc90004d06dd0 EFLAGS: 00010203
RAX: 000000000000005d RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000d6ac000 RSI: 0000000000000b2f RDI: 0000000000000b30
RBP: dffffc0000000000 R08: ffff888026dc1e00 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: dffffc0000000000
R13: ffff88805ba13000 R14: 00000000000002ec R15: ffff88805ba13000
FS:  00007f8c0504f6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8c0504ef98 CR3: 000000005aa85000 CR4: 00000000003506f0
----------------
Code disassembly (best guess):
   0:	55                   	push   %rbp
   1:	41 57                	push   %r15
   3:	41 56                	push   %r14
   5:	41 55                	push   %r13
   7:	41 54                	push   %r12
   9:	53                   	push   %rbx
   a:	48 89 f3             	mov    %rsi,%rbx
   d:	49 bc 00 00 00 00 00 	movabs $0xdffffc0000000000,%r12
  14:	fc ff df
  17:	e8 d0 be f3 f8       	call   0xf8f3beec
  1c:	4c 8d b3 ec 02 00 00 	lea    0x2ec(%rbx),%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 e3 00 00 00    	jne    0x11a
  37:	41 8b 2e             	mov    (%r14),%ebp
  3a:	31 ff                	xor    %edi,%edi
  3c:	89 ee                	mov    %ebp,%esi
  3e:	e8                   	.byte 0xe8
  3f:	59                   	pop    %rcx

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/16 09:51 linux-6.6.y 9247f4e6573a 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in hfsc_qlen_notify
2025/07/14 14:50 linux-6.6.y 59a2de10b81a d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in hfsc_qlen_notify
2025/07/14 14:49 linux-6.6.y 59a2de10b81a d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in hfsc_qlen_notify
* Struck through repros no longer work on HEAD.