[Linux kernel bug] divide error in wq_update_node_max_active
From: Sam Sun
Date: Tue Apr 23 2024 - 06:11:15 EST
Dear developers and maintainers,
We encountered a divide error bug while using our modified syzkaller.
It was tested against the latest upstream kernel (6.9-rc5). The kernel
was compiled by clang 14.0.0, and kernel config and C repro are
attached to this email. Kernel crash log is listed below.
```
divide error: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 PID: 21 Comm: cpuhp/1 Not tainted 6.9.0-rc5 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:wq_update_node_max_active+0x369/0x6b0 kernel/workqueue.c:1605
Code: 24 bf 00 00 00 80 44 89 fe e8 83 27 33 00 41 83 fc ff 75 0d 41
81 ff 00 00 00 80 0f 84 68 01 00 00 e8 fb 22 33 00 44 89 f8 99 <41> f7
fc 89 c5 89 c7 44 89 ee e8 a8 24 33 00 89 ef 8b 5c 24 04 89
RSP: 0018:ffffc9000018fbb0 EFLAGS: 00010293
RAX: 00000000000000ff RBX: 0000000000000001 RCX: ffff888100ada500
RDX: 0000000000000000 RSI: 00000000000000ff RDI: 0000000080000000
RBP: 0000000000000001 R08: ffffffff815b1fcd R09: 1ffff1100364ad72
R10: dffffc0000000000 R11: ffffed100364ad73 R12: 0000000000000000
R13: 0000000000000100 R14: 0000000000000000 R15: 00000000000000ff
FS: 0000000000000000(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb8c06ca6f8 CR3: 000000010d6c6000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<TASK>
workqueue_offline_cpu+0x56f/0x600 kernel/workqueue.c:6525
cpuhp_invoke_callback+0x4e1/0x870 kernel/cpu.c:194
cpuhp_thread_fun+0x411/0x7d0 kernel/cpu.c:1092
smpboot_thread_fn+0x544/0xa10 kernel/smpboot.c:164
kthread+0x2ed/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:244
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:wq_update_node_max_active+0x369/0x6b0 kernel/workqueue.c:1605
Code: 24 bf 00 00 00 80 44 89 fe e8 83 27 33 00 41 83 fc ff 75 0d 41
81 ff 00 00 00 80 0f 84 68 01 00 00 e8 fb 22 33 00 44 89 f8 99 <41> f7
fc 89 c5 89 c7 44 89 ee e8 a8 24 33 00 89 ef 8b 5c 24 04 89
RSP: 0018:ffffc9000018fbb0 EFLAGS: 00010293
RAX: 00000000000000ff RBX: 0000000000000001 RCX: ffff888100ada500
RDX: 0000000000000000 RSI: 00000000000000ff RDI: 0000000080000000
RBP: 0000000000000001 R08: ffffffff815b1fcd R09: 1ffff1100364ad72
R10: dffffc0000000000 R11: ffffed100364ad73 R12: 0000000000000000
R13: 0000000000000100 R14: 0000000000000000 R15: 00000000000000ff
FS: 0000000000000000(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb8c06ca6f8 CR3: 000000010d6c6000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
----------------
Code disassembly (best guess):
0: 24 bf and $0xbf,%al
2: 00 00 add %al,(%rax)
4: 00 80 44 89 fe e8 add %al,-0x170176bc(%rax)
a: 83 27 33 andl $0x33,(%rdi)
d: 00 41 83 add %al,-0x7d(%rcx)
10: fc cld
11: ff 75 0d push 0xd(%rbp)
14: 41 81 ff 00 00 00 80 cmp $0x80000000,%r15d
1b: 0f 84 68 01 00 00 je 0x189
21: e8 fb 22 33 00 call 0x332321
26: 44 89 f8 mov %r15d,%eax
29: 99 cltd
* 2a: 41 f7 fc idiv %r12d <-- trapping instruction
2d: 89 c5 mov %eax,%ebp
2f: 89 c7 mov %eax,%edi
31: 44 89 ee mov %r13d,%esi
34: e8 a8 24 33 00 call 0x3324e1
39: 89 ef mov %ebp,%edi
3b: 8b 5c 24 04 mov 0x4(%rsp),%ebx
3f: 89 .byte 0x89
```
If you have any questions, please contact us.
Reported by Yue Sun <samsun1006219@xxxxxxxxx>
Reported by xingwei lee <xrivendell7@xxxxxxxxx>
Best Regards,
Yue
Attachment:
config
Description: Binary data
#define _GNU_SOURCE
#include <endian.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
static long syz_mod_dev(volatile long a0, volatile long a1, volatile long a2,
volatile long a3, volatile long a4, volatile long a5)
{
int fd, sysfd;
char buf[1024], sysbuf[1024], input[1024];
char* hash;
char dev_num;
dev_num = 0;
strncpy(buf, (char*)a0, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = 0;
while ((hash = strchr(buf, '#'))) {
*hash = '0' + (char)(a1 % 10);
a1 /= 10;
if (dev_num == 0)
dev_num = *hash;
}
fd = open(buf, a2, 0);
strncpy(sysbuf, (char*)a3, sizeof(sysbuf) - 1);
sysbuf[sizeof(sysbuf) - 1] = 0;
if ((hash = strchr(sysbuf, '#'))) {
*hash = dev_num;
while ((hash = strchr(sysbuf, '#'))) {
*hash = '0' + (char)(a1 % 10);
a1 /= 10;
}
}
sysfd = open(sysbuf, O_RDWR, 0);
strncpy(input, (char*)a4, sizeof(input) - 1);
input[sizeof(input) - 1] = 0;
hash = strchr(input, '\0');
sysfd = write(sysfd, input, hash - input + 1);
return fd;
}
uint64_t r[1] = {0xffffffffffffffff};
int main(void)
{
syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
/*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul,
/*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
/*offset=*/0ul);
syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
/*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
/*offset=*/0ul);
intptr_t res = 0;
memcpy((void*)0x20000340, "/dev/nvme-fabrics\000", 18);
memcpy((void*)0x20000380,
"/sys/devices/virtual/workqueue/nvme-delete-wq/cpumask\000", 54);
memcpy((void*)0x200003c0, "2\000", 2);
syz_mod_dev(/*dev=*/0x20000340, /*id=*/0, /*flags=*/0, /*file=*/0x20000380,
/*buf=*/0x200003c0, /*fd=*/-1);
memcpy((void*)0x20000040, "/sys/devices/system/cpu/cpu1/online\000", 36);
res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x20000040ul,
/*flags=*/2ul, /*mode=*/0ul);
if (res != -1)
r[0] = res;
sprintf((char*)0x20002780, "%020llu", (long long)0);
*(uint8_t*)0x20002794 = 0;
syscall(__NR_write, /*fd=*/r[0], /*buf=*/0x20002780ul, /*len=*/0x15ul);
return 0;
}