syzbot


general protection fault in qdisc_tree_reduce_backlog

Status: upstream: reported C repro on 2025/07/16 10:37
Reported-by: syzbot+2afda2024f822f01e1b4@syzkaller.appspotmail.com
First crash: 2d00h, last: 3h12m
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in qdisc_tree_reduce_backlog net 8 C done 254 1h06m 12d 23/29 upstream: reported C repro on 2025/07/04 05:20
linux-6.1 BUG: unable to handle kernel paging request in qdisc_tree_reduce_backlog origin:lts-only 8 C error 4 1d04h 5d15h 0/3 upstream: reported C repro on 2025/07/10 22:10
linux-5.15 BUG: unable to handle kernel paging request in qdisc_tree_reduce_backlog origin:lts-only 8 C 8 2h13m 3d03h 0/3 upstream: reported C repro on 2025/07/13 10:38

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 0 PID: 288 Comm: syz-executor213 Not tainted 5.15.188-syzkaller-00606-g6b619c45dff5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:qdisc_tree_reduce_backlog+0x181/0x340 net/sched/sch_api.c:795
Code: e8 f4 89 d7 fd 4d 89 ef 83 7d d0 00 74 0a e8 d6 12 99 fd e9 80 00 00 00 4d 8b 36 49 8d 46 20 48 89 c1 48 c1 e9 03 48 89 4d b8 <80> 3c 19 00 48 89 45 d0 74 0d 48 8b 7d d0 e8 bc 89 d7 fd 48 8b 45
RSP: 0018:ffffc900009c6f08 EFLAGS: 00010202
RAX: 0000000000000020 RBX: dffffc0000000000 RCX: 0000000000000004
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900009c6f50 R08: ffff8881057a4f00 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000000 R12: 00000000000affe0
R13: ffff8881059fec00 R14: 0000000000000000 R15: ffff8881059fec00
FS:  000055555fbf5380(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ea3da3b028 CR3: 00000001219d8000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 codel_change+0x8d1/0xc00 net/sched/sch_codel.c:183
 codel_init+0x1a8/0x390 net/sched/sch_codel.c:202
 qdisc_create+0x7ed/0x11a0 net/sched/sch_api.c:1261
 tc_modify_qdisc+0x896/0x1480 net/sched/sch_api.c:-1
 rtnetlink_rcv_msg+0x9e4/0xb90 net/core/rtnetlink.c:5650
 netlink_rcv_skb+0x1e0/0x430 net/netlink/af_netlink.c:2493
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:5668
 netlink_unicast_kernel net/netlink/af_netlink.c:1315 [inline]
 netlink_unicast+0x87c/0xa40 net/netlink/af_netlink.c:1341
 netlink_sendmsg+0x86a/0xb70 net/netlink/af_netlink.c:1909
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2436
 ___sys_sendmsg+0x1f0/0x260 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]
 __x64_sys_sendmsg+0x1e2/0x2a0 net/socket.c:2526
 x64_sys_call+0x4b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f249c0745a9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdef653c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f249c0745a9
RDX: 0000000000004000 RSI: 0000200000000280 RDI: 0000000000000003
RBP: 00007f249c0e7610 R08: 0000000000000001 R09: 00000000000ac5f8
R10: 000000000000000a R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffdef653e48 R14: 0000200000000788 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 52f0b48c1e49cfc8 ]---
RIP: 0010:qdisc_tree_reduce_backlog+0x181/0x340 net/sched/sch_api.c:795
Code: e8 f4 89 d7 fd 4d 89 ef 83 7d d0 00 74 0a e8 d6 12 99 fd e9 80 00 00 00 4d 8b 36 49 8d 46 20 48 89 c1 48 c1 e9 03 48 89 4d b8 <80> 3c 19 00 48 89 45 d0 74 0d 48 8b 7d d0 e8 bc 89 d7 fd 48 8b 45
RSP: 0018:ffffc900009c6f08 EFLAGS: 00010202
RAX: 0000000000000020 RBX: dffffc0000000000 RCX: 0000000000000004
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900009c6f50 R08: ffff8881057a4f00 R09: 0000000000000002
R10: 00000000ffffffff R11: 0000000000000000 R12: 00000000000affe0
R13: ffff8881059fec00 R14: 0000000000000000 R15: ffff8881059fec00
FS:  000055555fbf5380(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ea3da3b028 CR3: 00000001219d8000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	e8 f4 89 d7 fd       	call   0xfdd789f9
   5:	4d 89 ef             	mov    %r13,%r15
   8:	83 7d d0 00          	cmpl   $0x0,-0x30(%rbp)
   c:	74 0a                	je     0x18
   e:	e8 d6 12 99 fd       	call   0xfd9912e9
  13:	e9 80 00 00 00       	jmp    0x98
  18:	4d 8b 36             	mov    (%r14),%r14
  1b:	49 8d 46 20          	lea    0x20(%r14),%rax
  1f:	48 89 c1             	mov    %rax,%rcx
  22:	48 c1 e9 03          	shr    $0x3,%rcx
  26:	48 89 4d b8          	mov    %rcx,-0x48(%rbp)
* 2a:	80 3c 19 00          	cmpb   $0x0,(%rcx,%rbx,1) <-- trapping instruction
  2e:	48 89 45 d0          	mov    %rax,-0x30(%rbp)
  32:	74 0d                	je     0x41
  34:	48 8b 7d d0          	mov    -0x30(%rbp),%rdi
  38:	e8 bc 89 d7 fd       	call   0xfdd789f9
  3d:	48                   	rex.W
  3e:	8b                   	.byte 0x8b
  3f:	45                   	rex.RB

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/16 10:27 android13-5.15-lts 6b619c45dff5 124ec9cc .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in qdisc_tree_reduce_backlog
2025/07/16 10:06 android13-5.15-lts 6b619c45dff5 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in qdisc_tree_reduce_backlog
2025/07/16 10:06 android13-5.15-lts 6b619c45dff5 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in qdisc_tree_reduce_backlog
2025/07/16 09:36 android13-5.15-lts 6b619c45dff5 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in qdisc_tree_reduce_backlog
2025/07/14 12:48 android13-5.15-lts eabc268e4fb2 d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in qdisc_tree_reduce_backlog
2025/07/14 12:48 android13-5.15-lts eabc268e4fb2 d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in qdisc_tree_reduce_backlog
2025/07/14 12:47 android13-5.15-lts eabc268e4fb2 d8fc7335 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in qdisc_tree_reduce_backlog
* Struck through repros no longer work on HEAD.