syzbot


general protection fault in drr_qlen_notify

Status: upstream: reported on 2025/07/14 23:18
Reported-by: syzbot+0a760d7df2b7372532ad@syzkaller.appspotmail.com
First crash: 6d17h, last: 3d21h
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 BUG: unable to handle kernel paging request in drr_qlen_notify origin:lts-only 8 C 15 4d15h 10d 0/3 upstream: reported C repro on 2025/07/10 19:29
upstream general protection fault in drr_qlen_notify net 10 C done 101 8d13h 17d 27/29 upstream: reported C repro on 2025/07/04 05:20
linux-6.1 BUG: unable to handle kernel paging request in drr_qlen_notify 8 10 4d00h 10d 0/3 upstream: reported on 2025/07/10 23:44

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
CPU: 1 PID: 7829 Comm: syz.2.497 Not tainted 6.6.98-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__list_del_entry_valid_or_report+0x23/0x130 lib/list_debug.c:49
Code: 00 00 00 00 00 66 90 f3 0f 1e fa 41 57 41 56 41 54 53 48 89 fb 49 bc 00 00 00 00 00 fc ff df 48 83 c7 08 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 05 e8 11 ca b7 fd 4c 8b 7b 08 48 89 d8 48 c1 e8
RSP: 0018:ffffc9000f176d48 EFLAGS: 00010202
RAX: 000000000000000b RBX: 0000000000000050 RCX: 0000000000080000
RDX: ffffc9000e4f0000 RSI: 0000000000001357 RDI: 0000000000000058
RBP: dffffc0000000000 R08: ffff88802fd75a00 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000050 R15: ffff888076eff800
FS:  00007f3d253ff6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000019580 CR3: 0000000030311000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 __list_del_entry_valid include/linux/list.h:124 [inline]
 __list_del_entry include/linux/list.h:215 [inline]
 list_del_init include/linux/list.h:287 [inline]
 drr_qlen_notify+0x2c/0xf0 net/sched/sch_drr.c:238
 qdisc_tree_reduce_backlog+0x28b/0x470 net/sched/sch_api.c:810
 fq_codel_change+0xa2d/0xde0 net/sched/sch_fq_codel.c:440
 fq_codel_init+0x361/0x970 net/sched/sch_fq_codel.c:477
 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: 0033:0x7f3d2558e929
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:00007f3d253ff038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f3d257b6080 RCX: 00007f3d2558e929
RDX: 0000000000000800 RSI: 0000200000000100 RDI: 0000000000000004
RBP: 00007f3d25610ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f3d257b6080 R15: 00007fff8a7580c8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__list_del_entry_valid_or_report+0x23/0x130 lib/list_debug.c:49
Code: 00 00 00 00 00 66 90 f3 0f 1e fa 41 57 41 56 41 54 53 48 89 fb 49 bc 00 00 00 00 00 fc ff df 48 83 c7 08 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 05 e8 11 ca b7 fd 4c 8b 7b 08 48 89 d8 48 c1 e8
RSP: 0018:ffffc9000f176d48 EFLAGS: 00010202
RAX: 000000000000000b RBX: 0000000000000050 RCX: 0000000000080000
RDX: ffffc9000e4f0000 RSI: 0000000000001357 RDI: 0000000000000058
RBP: dffffc0000000000 R08: ffff88802fd75a00 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000002 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000050 R15: ffff888076eff800
FS:  00007f3d253ff6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000019580 CR3: 0000000030311000 CR4: 00000000003506e0
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	00 00                	add    %al,(%rax)
   4:	00 66 90             	add    %ah,-0x70(%rsi)
   7:	f3 0f 1e fa          	endbr64
   b:	41 57                	push   %r15
   d:	41 56                	push   %r14
   f:	41 54                	push   %r12
  11:	53                   	push   %rbx
  12:	48 89 fb             	mov    %rdi,%rbx
  15:	49 bc 00 00 00 00 00 	movabs $0xdffffc0000000000,%r12
  1c:	fc ff df
  1f:	48 83 c7 08          	add    $0x8,%rdi
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1) <-- trapping instruction
  2f:	74 05                	je     0x36
  31:	e8 11 ca b7 fd       	call   0xfdb7ca47
  36:	4c 8b 7b 08          	mov    0x8(%rbx),%r15
  3a:	48 89 d8             	mov    %rbx,%rax
  3d:	48                   	rex.W
  3e:	c1                   	.byte 0xc1
  3f:	e8                   	.byte 0xe8

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/17 18:40 linux-6.6.y 9247f4e6573a 0d1223f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in drr_qlen_notify
2025/07/15 09:34 linux-6.6.y 9247f4e6573a 03fcfc4b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in drr_qlen_notify
2025/07/14 23:18 linux-6.6.y 9247f4e6573a d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in drr_qlen_notify
* Struck through repros no longer work on HEAD.