syzbot


general protection fault in htb_qlen_notify

Status: upstream: reported C repro on 2025/07/10 18:56
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+1be8ab4d23babd1c7655@syzkaller.appspotmail.com
First crash: 4d08h, last: 2d13h
Bug presence (2)
Date Name Commit Repro Result
2025/07/12 linux-6.1.y (ToT) dfc486ec9cce C [report] general protection fault in htb_qlen_notify
2025/07/12 upstream (ToT) 379f604cc3dc C Didn't crash
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 general protection fault in htb_qlen_notify origin:lts-only 8 C 9 3d04h 4d08h 0/3 upstream: reported C repro on 2025/07/10 18:58
android-5-15 general protection fault in htb_qlen_notify 2 1 13h46m 13h45m 0/2 premoderation: reported on 2025/07/14 13:36
upstream general protection fault in htb_qlen_notify net 10 C done 166 1d22h 11d 23/29 upstream: reported C repro on 2025/07/03 08:17

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000037: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000001b8-0x00000000000001bf]
CPU: 1 PID: 4422 Comm: syz.0.16 Not tainted 6.1.144-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:htb_deactivate net/sched/sch_htb.c:610 [inline]
RIP: 0010:htb_qlen_notify+0x2d/0xb0 net/sched/sch_htb.c:1486
Code: 41 56 41 55 41 54 53 49 89 f6 49 89 ff 49 bc 00 00 00 00 00 fc ff df e8 f1 a5 38 f9 49 8d 9e b8 01 00 00 49 89 dd 49 c1 ed 03 <43> 0f b6 44 25 00 84 c0 75 48 8b 2b 31 ff 89 ee e8 2e a9 38 f9 85
RSP: 0018:ffffc900032d6e90 EFLAGS: 00010202
RAX: ffffffff8848319f RBX: 00000000000001b8 RCX: ffff888079391dc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88807a750000
RBP: dffffc0000000000 R08: ffff888079391dc0 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000037 R14: 0000000000000000 R15: ffff88807a750000
FS:  0000555590528500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000240 CR3: 00000000281c6000 CR4: 00000000003506e0
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: 0033:0x7faef638e929
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:00007ffe795e3868 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007faef65b5fa0 RCX: 00007faef638e929
RDX: 000000000000c010 RSI: 0000200000000280 RDI: 0000000000000003
RBP: 00007faef6410b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007faef65b5fa0 R14: 00007faef65b5fa0 R15: 0000000000000003
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:htb_deactivate net/sched/sch_htb.c:610 [inline]
RIP: 0010:htb_qlen_notify+0x2d/0xb0 net/sched/sch_htb.c:1486
Code: 41 56 41 55 41 54 53 49 89 f6 49 89 ff 49 bc 00 00 00 00 00 fc ff df e8 f1 a5 38 f9 49 8d 9e b8 01 00 00 49 89 dd 49 c1 ed 03 <43> 0f b6 44 25 00 84 c0 75 48 8b 2b 31 ff 89 ee e8 2e a9 38 f9 85
RSP: 0018:ffffc900032d6e90 EFLAGS: 00010202
RAX: ffffffff8848319f RBX: 00000000000001b8 RCX: ffff888079391dc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88807a750000
RBP: dffffc0000000000 R08: ffff888079391dc0 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000037 R14: 0000000000000000 R15: ffff88807a750000
FS:  0000555590528500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000240 CR3: 00000000281c6000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	41 56                	push   %r14
   2:	41 55                	push   %r13
   4:	41 54                	push   %r12
   6:	53                   	push   %rbx
   7:	49 89 f6             	mov    %rsi,%r14
   a:	49 89 ff             	mov    %rdi,%r15
   d:	49 bc 00 00 00 00 00 	movabs $0xdffffc0000000000,%r12
  14:	fc ff df
  17:	e8 f1 a5 38 f9       	call   0xf938a60d
  1c:	49 8d 9e b8 01 00 00 	lea    0x1b8(%r14),%rbx
  23:	49 89 dd             	mov    %rbx,%r13
  26:	49 c1 ed 03          	shr    $0x3,%r13
* 2a:	43 0f b6 44 25 00    	movzbl 0x0(%r13,%r12,1),%eax <-- trapping instruction
  30:	84 c0                	test   %al,%al
  32:	75 48                	jne    0x7c
  34:	8b 2b                	mov    (%rbx),%ebp
  36:	31 ff                	xor    %edi,%edi
  38:	89 ee                	mov    %ebp,%esi
  3a:	e8 2e a9 38 f9       	call   0xf938a96d
  3f:	85                   	.byte 0x85

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/11 09:38 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in htb_qlen_notify
2025/07/10 22:36 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 htb_qlen_notify
2025/07/10 18:56 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 htb_qlen_notify
2025/07/10 18:56 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 htb_qlen_notify
* Struck through repros no longer work on HEAD.