[syzbot] [net?] divide error in taprio_update_queue_max_sdu

From: syzbot
Date: Mon May 27 2024 - 09:22:44 EST

Hello,

syzbot found the following issue on:

HEAD commit: 4b377b4868ef kprobe/ftrace: fix build error due to bad fun..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11ab31a4980000
kernel config: https://syzkaller.appspot.com/x/.config?x=17ffd15f654c98ba
dashboard link: https://syzkaller.appspot.com/bug?extid=233e6e0ea2ba2c86fa79
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6f4c61bc9252/disk-4b377b48.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/841f1b24d3a1/vmlinux-4b377b48.xz
kernel image: https://storage.googleapis.com/syzbot-assets/017b655dca3d/bzImage-4b377b48.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+233e6e0ea2ba2c86fa79@xxxxxxxxxxxxxxxxxxxxxxxxx

Oops: divide error: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 PID: 15391 Comm: syz-executor.0 Not tainted 6.9.0-syzkaller-08544-g4b377b4868ef #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:div_u64_rem include/linux/math64.h:29 [inline]
RIP: 0010:div_u64 include/linux/math64.h:130 [inline]
RIP: 0010:duration_to_length net/sched/sch_taprio.c:259 [inline]
RIP: 0010:taprio_update_queue_max_sdu+0x287/0x870 net/sched/sch_taprio.c:288
Code: be 08 00 00 00 e8 99 5b 6a f8 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 13 59 6a f8 48 8b 03 89 c1 48 89 e8 31 d2 <48> f7 f1 48 89 c5 48 83 7c 24 50 00 4c 8b 74 24 30 74 47 e8 c1 19
RSP: 0018:ffffc9000506eb38 EFLAGS: 00010246
RAX: 0000000000001f40 RBX: ffff88802f3562e0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88802f3562e0
RBP: 0000000000001f40 R08: ffff88802f3562e7 R09: 1ffff11005e6ac5c
R10: dffffc0000000000 R11: ffffed1005e6ac5d R12: 00000000ffffffff
R13: dffffc0000000000 R14: ffff88801ef59400 R15: 00000000003f0008
FS: 00007fee340bf6c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2c524000 CR3: 0000000024a52000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
taprio_change+0x2dce/0x42d0 net/sched/sch_taprio.c:1911
taprio_init+0x9da/0xc80 net/sched/sch_taprio.c:2112
qdisc_create+0x9d4/0x11a0 net/sched/sch_api.c:1355
tc_modify_qdisc+0xa26/0x1e40 net/sched/sch_api.c:1777
rtnetlink_rcv_msg+0x89b/0x10d0 net/core/rtnetlink.c:6595
netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2564
netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1361
netlink_sendmsg+0x8e1/0xcb0 net/netlink/af_netlink.c:1905
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x221/0x270 net/socket.c:745
____sys_sendmsg+0x525/0x7d0 net/socket.c:2584
___sys_sendmsg net/socket.c:2638 [inline]
__sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fee3327cee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fee340bf0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fee333abf80 RCX: 00007fee3327cee9
RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 000000000000000e
RBP: 00007fee332c949e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fee333abf80 R15: 00007fff3d596598
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:div_u64_rem include/linux/math64.h:29 [inline]
RIP: 0010:div_u64 include/linux/math64.h:130 [inline]
RIP: 0010:duration_to_length net/sched/sch_taprio.c:259 [inline]
RIP: 0010:taprio_update_queue_max_sdu+0x287/0x870 net/sched/sch_taprio.c:288
Code: be 08 00 00 00 e8 99 5b 6a f8 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 13 59 6a f8 48 8b 03 89 c1 48 89 e8 31 d2 <48> f7 f1 48 89 c5 48 83 7c 24 50 00 4c 8b 74 24 30 74 47 e8 c1 19
RSP: 0018:ffffc9000506eb38 EFLAGS: 00010246
RAX: 0000000000001f40 RBX: ffff88802f3562e0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff88802f3562e0
RBP: 0000000000001f40 R08: ffff88802f3562e7 R09: 1ffff11005e6ac5c
R10: dffffc0000000000 R11: ffffed1005e6ac5d R12: 00000000ffffffff
R13: dffffc0000000000 R14: ffff88801ef59400 R15: 00000000003f0008
FS: 00007fee340bf6c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31424000 CR3: 0000000024a52000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: be 08 00 00 00 mov $0x8,%esi
5: e8 99 5b 6a f8 call 0xf86a5ba3
a: 48 89 d8 mov %rbx,%rax
d: 48 c1 e8 03 shr $0x3,%rax
11: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1)
16: 74 08 je 0x20
18: 48 89 df mov %rbx,%rdi
1b: e8 13 59 6a f8 call 0xf86a5933
20: 48 8b 03 mov (%rbx),%rax
23: 89 c1 mov %eax,%ecx
25: 48 89 e8 mov %rbp,%rax
28: 31 d2 xor %edx,%edx
* 2a: 48 f7 f1 div %rcx <-- trapping instruction
2d: 48 89 c5 mov %rax,%rbp
30: 48 83 7c 24 50 00 cmpq $0x0,0x50(%rsp)
36: 4c 8b 74 24 30 mov 0x30(%rsp),%r14
3b: 74 47 je 0x84
3d: e8 .byte 0xe8
3e: c1 .byte 0xc1
3f: 19 .byte 0x19


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