syzbot


general protection fault in hfsc_qlen_notify

Status: upstream: reported on 2025/07/10 21:19
Reported-by: syzbot+0fa6e6227699266e85ba@syzkaller.appspotmail.com
First crash: 10d, last: 3d22h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 general protection fault in hfsc_qlen_notify 2 3 5d05h 7d00h 0/2 upstream: reported on 2025/07/14 14:50
upstream general protection fault in hfsc_qlen_notify net 10 C 161 4d04h 18d 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: 7034 Comm: syz.0.659 Not tainted 6.1.145-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:hfsc_qlen_notify+0x2a/0x160 net/sched/sch_hfsc.c:1235
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 f4 53 39 f9 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 2d
RSP: 0018:ffffc90003346e90 EFLAGS: 00010203
RAX: 000000000000005d RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc900056b9000 RSI: 00000000000002d3 RDI: 00000000000002d4
RBP: dffffc0000000000 R08: ffff888077829dc0 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: dffffc0000000000
R13: ffff8880523d5000 R14: 00000000000002ec R15: ffff8880523d5000
FS:  00007fd2ea5db6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000007a5ce000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 qdisc_tree_reduce_backlog+0x287/0x470 net/sched/sch_api.c:807
 codel_change+0x970/0xdb0 net/sched/sch_codel.c:177
 codel_init+0x1d4/0x3a0 net/sched/sch_codel.c:196
 qdisc_create+0x7cb/0x1090 net/sched/sch_api.c:1310
 tc_modify_qdisc+0xb0f/0x1be0 net/sched/sch_api.c:-1
 rtnetlink_rcv_msg+0x79b/0xed0 net/core/rtnetlink.c:6153
 netlink_rcv_skb+0x1de/0x420 net/netlink/af_netlink.c:2493
 netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
 netlink_unicast+0x74c/0x8c0 net/netlink/af_netlink.c:1337
 netlink_sendmsg+0x89e/0xbc0 net/netlink/af_netlink.c:1859
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x59b/0x970 net/socket.c:2519
 ___sys_sendmsg+0x21c/0x290 net/socket.c:2573
 __sys_sendmsg net/socket.c:2602 [inline]
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg+0x19e/0x270 net/socket.c:2609
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd2e978e929
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:00007fd2ea5db038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd2e99b5fa0 RCX: 00007fd2e978e929
RDX: 0000000000004000 RSI: 0000200000000040 RDI: 0000000000000007
RBP: 00007fd2e9810ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd2e99b5fa0 R15: 00007ffea80ac188
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:hfsc_qlen_notify+0x2a/0x160 net/sched/sch_hfsc.c:1235
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 f4 53 39 f9 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 2d
RSP: 0018:ffffc90003346e90 EFLAGS: 00010203
RAX: 000000000000005d RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc900056b9000 RSI: 00000000000002d3 RDI: 00000000000002d4
RBP: dffffc0000000000 R08: ffff888077829dc0 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: dffffc0000000000
R13: ffff8880523d5000 R14: 00000000000002ec R15: ffff8880523d5000
FS:  00007fd2ea5db6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000007a5ce000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
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 f4 53 39 f9       	call   0xf9395410
  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:	2d                   	.byte 0x2d

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/17 16:18 linux-6.1.y f2198ea7eb3e 0d1223f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in hfsc_qlen_notify
2025/07/15 00:33 linux-6.1.y f2198ea7eb3e d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in hfsc_qlen_notify
2025/07/15 00:33 linux-6.1.y f2198ea7eb3e d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in hfsc_qlen_notify
2025/07/10 21:18 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in hfsc_qlen_notify
* Struck through repros no longer work on HEAD.