drivers/net/hamradio: divide error in hdlcdrv_ioctl

[Andrey Konovalov]

Hi,

I've got the following error report while fuzzing the kernel with syzkaller.

On commit 2ea659a9ef488125eb46da6eb571de5eae5c43f6 (4.12-rc1).

A reproducer and .config are attached.

divide error: 0000 [#1] SMP KASAN
Modules linked in:
CPU: 1 PID: 4019 Comm: a.out Not tainted 4.12.0-rc1+ #363
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff88006b97c200 task.stack: ffff880062098000
RIP: 0010:hdlcdrv_ioctl+0x8a3/0x1a50 drivers/net/hamradio/hdlcdrv.c:579
RSP: 0018:ffff88006209f898 EFLAGS: 00010246
RAX: 000000007fffffff RBX: ffff88006209f8d0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88006888abd0
RBP: ffff88006209f9b8 R08: 1ffff1000c413e8a R09: 1ffff1000c413e6a
R10: ffff88006b97c200 R11: 0000000000000001 R12: 1ffff1000c413f16
R13: ffff88006888a100 R14: 0000000000000000 R15: 00000000005b78f4
FS:  00007fb533884700(0000) GS:ffff88006cb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002026b000 CR3: 0000000065576000 CR4: 00000000000006e0
Call Trace:
 dev_ifsioc+0x53f/0x9f0 net/core/dev_ioctl.c:338
 dev_ioctl+0xc3c/0x1160 net/core/dev_ioctl.c:555
 sock_ioctl+0x169/0x440 net/socket.c:944
 vfs_ioctl fs/ioctl.c:45
 do_vfs_ioctl+0x1bf/0x1660 fs/ioctl.c:685
 SYSC_ioctl fs/ioctl.c:700
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
 entry_SYSCALL_64_fastpath+0x1f/0xbe arch/x86/entry/entry_64.S:204
RIP: 0033:0x7fb532f96b79
RSP: 002b:00007fffac2839f8 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fffac283b60 RCX: 00007fb532f96b79
RDX: 00000000208f1fd8 RSI: 00000100000089f0 RDI: 0000000000000003
RBP: 00000000004004e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fffac283b60 R14: 0000000000000000 R15: 0000000000000000
Code: 45 8b be 48 ff ff ff 48 89 fa 48 c1 ea 03 0f b6 04 02 84 c0 74
08 3c 03 0f 8e 8b 0e 00 00 45 8b b5 d0 0a 00 00 b8 ff ff ff 7f 99 <41>
f7 fe 41 39 c7 0f 87 89 0c 00 00 e8 ac e5 7e fe 49 8d bd d8
RIP: hdlcdrv_ioctl+0x8a3/0x1a50 RSP: ffff88006209f898
---[ end trace 204af21e5cc80963 ]---
qemu: terminating on signal 15 from pid 141905
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#ifndef __NR_mmap
#define __NR_mmap 9
#endif
#ifndef __NR_socket
#define __NR_socket 41
#endif
#ifndef __NR_ioctl
#define __NR_ioctl 16
#endif

#define _GNU_SOURCE

#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>

#include <linux/capability.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <linux/kvm.h>
#include <linux/sched.h>
#include <net/if_arp.h>

#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <pthread.h>
#include <setjmp.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static uintptr_t execute_syscall(int nr, uintptr_t a0, uintptr_t a1,
                                 uintptr_t a2, uintptr_t a3,
                                 uintptr_t a4, uintptr_t a5,
                                 uintptr_t a6, uintptr_t a7,
                                 uintptr_t a8)
{
  switch (nr) {
  default:
    return syscall(nr, a0, a1, a2, a3, a4, a5);
  }
}

long r[6];

void loop()
{
  memset(r, -1, sizeof(r));
  r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x8f2000ul, 0x3ul,
                         0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
  r[1] = execute_syscall(__NR_socket, 0xaul, 0x5ul, 0x84ul, 0, 0, 0, 0,
                         0, 0);
  (memcpy((void*)0x208f1fd8,
                    "\x62\x63\x73\x68\x30\x00\x00\x00\x00\x00\x00\x00"
                    "\x00\x00\x00\x00",
                    16));
  (*(uint64_t*)0x208f1fe8 = (uint64_t)0x2026b000);
  (memcpy((void*)0x2026b000,
                    "\x15\x00\x00\x00\x6d\x3f\x00\x00\xf4\x78\x5b\x00"
                    "\x00\x00\x06\x00\x41\x00\x00\x00\x05\x00\x11\x00"
                    "\x80\x00\x00\xdf\x22\x68\x8a\x23",
                    32));
  r[5] = execute_syscall(__NR_ioctl, r[1], 0x100000089f0ul,
                         0x208f1fd8ul, 0, 0, 0, 0, 0, 0);
}

int main()
{
  loop();
  return 0;
}

Attachment: .config
Description: Binary data