net/netlink: null-ptr-deref in netlink_dump/lock_acquire

* net/netlink: null-ptr-deref in netlink_dump/lock_acquire
@ 2016-10-19 14:13 Andrey Konovalov
  2016-11-03  0:15 ` Andrey Konovalov
  0 siblings, 1 reply; 9+ messages in thread
From: Andrey Konovalov @ 2016-10-19 14:13 UTC (permalink / raw)
  To: David S. Miller, Johannes Berg, Florian Westphal, Michal Hocko,
	Vlastimil Babka, Herbert Xu, David Decotigny, Mel Gorman,
	David Herrmann, Tom Herbert, Eric Dumazet, netdev, LKML
  Cc: syzkaller, Kostya Serebryany, Alexander Potapenko, Dmitry Vyukov

[-- Attachment #1: Type: text/plain, Size: 3284 bytes --]

Hi,

I've got the following error report while running the syzkaller fuzzer:

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Modules linked in:
CPU: 1 PID: 3933 Comm: syz-executor Not tainted 4.9.0-rc1+ #230
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff88006b79d800 task.stack: ffff88006bbc0000
RIP: 0010:[<ffffffff8120872d>]  [<ffffffff8120872d>]
__lock_acquire+0x12d/0x3450 kernel/locking/lockdep.c:3221
RSP: 0018:ffff88006bbc7420  EFLAGS: 00010006
RAX: 0000000000000046 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: 000000000000000c RSI: 0000000000000000 RDI: 0000000000000003
RBP: ffff88006bbc75c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff85f42240 R12: ffff88006b79d800
R13: ffffffff84bfe4e0 R14: 0000000000000001 R15: 0000000000000060
FS:  00007fd9c41cc700(0000) GS:ffff88006cd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000451f80 CR3: 00000000638f0000 CR4: 00000000000006e0
Stack:
 0000000000000000 ffff88006bbc0000 ffff88006bbc8000 0000000000000000
 0000000000000002 ffff88006b79d800 0000000000000000 ffff88006bbc7f48
 ffffffff852adc60 0000000000000000 ffffffff852adc64 1ffffffff0b40135
Call Trace:
 [<ffffffff8120c5ae>] lock_acquire+0x17e/0x340 kernel/locking/lockdep.c:3746
 [<     inline     >] __mutex_lock_common kernel/locking/mutex.c:521
 [<ffffffff83fb6fe1>] mutex_lock_nested+0xb1/0x890 kernel/locking/mutex.c:621
 [<ffffffff82db6fd0>] netlink_dump+0x50/0xac0 net/netlink/af_netlink.c:2067
 [<ffffffff82dba381>] __netlink_dump_start+0x501/0x770
net/netlink/af_netlink.c:2200
 [<ffffffff82dc35b2>] genl_family_rcv_msg+0xa02/0xc80
net/netlink/genetlink.c:595
 [<ffffffff82dc39e6>] genl_rcv_msg+0x1b6/0x270 net/netlink/genetlink.c:658
 [<ffffffff82dc1a70>] netlink_rcv_skb+0x2c0/0x3b0 net/netlink/af_netlink.c:2281
 [<ffffffff82dc2b98>] genl_rcv+0x28/0x40 net/netlink/genetlink.c:669
 [<     inline     >] netlink_unicast_kernel net/netlink/af_netlink.c:1214
 [<ffffffff82dc0329>] netlink_unicast+0x5a9/0x880 net/netlink/af_netlink.c:1240
 [<ffffffff82dc0fb7>] netlink_sendmsg+0x9b7/0xce0 net/netlink/af_netlink.c:1786
 [<     inline     >] sock_sendmsg_nosec net/socket.c:606
 [<ffffffff82b7075c>] sock_sendmsg+0xcc/0x110 net/socket.c:616
 [<ffffffff82b709c1>] sock_write_iter+0x221/0x3b0 net/socket.c:814
 [<     inline     >] new_sync_write fs/read_write.c:499
 [<ffffffff8151c944>] __vfs_write+0x334/0x570 fs/read_write.c:512
 [<ffffffff8152045b>] vfs_write+0x17b/0x500 fs/read_write.c:560
 [<     inline     >] SYSC_write fs/read_write.c:607
 [<ffffffff81523d84>] SyS_write+0xd4/0x1a0 fs/read_write.c:599
 [<ffffffff83fc0141>] entry_SYSCALL_64_fastpath+0x1f/0xc2
arch/x86/entry/entry_64.S:209
Code: 0f 1f 44 00 00 f6 c4 02 0f 85 24 0a 00 00 44 8b 35 c9 61 8b 03
45 85 f6 74 2c 4c 89 fa 48 bb 00 00 00 00 00 fc ff df 48 c1 ea 03 <80>
3c 1a 00 0f 85 04 2f 00 00 49 81 3f a0 dc 2a 85 41 be 00 00
RIP  [<ffffffff8120872d>] __lock_acquire+0x12d/0x3450
kernel/locking/lockdep.c:3221
 RSP <ffff88006bbc7420>
---[ end trace 685b3c182bf7f25c ]---

The reproducer is attached.

On commit 1a1891d762d6e64daf07b5be4817e3fbb29e3c59 (Oct 18).

[-- Attachment #2: netlink.c --]
[-- Type: text/x-csrc, Size: 5880 bytes --]

// autogenerated by syzkaller (http://github.com/google/syzkaller)

#ifndef __NR_syz_test
#define __NR_syz_test 1000001
#endif
#ifndef __NR_socket
#define __NR_socket 41
#endif
#ifndef __NR_write
#define __NR_write 1
#endif
#ifndef __NR_syz_fuse_mount
#define __NR_syz_fuse_mount 1000004
#endif
#ifndef __NR_syz_open_dev
#define __NR_syz_open_dev 1000002
#endif
#ifndef __NR_mmap
#define __NR_mmap 9
#endif
#ifndef __NR_syz_fuseblk_mount
#define __NR_syz_fuseblk_mount 1000005
#endif
#ifndef __NR_syz_open_pts
#define __NR_syz_open_pts 1000003
#endif

#include <fcntl.h>
#include <pthread.h>
#include <setjmp.h>
#include <signal.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

__thread int skip_segv;
__thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* uctx)
{
  if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED))
    _longjmp(segv_env, 1);
  exit(sig);
}

static void install_segv_handler()
{
  struct sigaction sa;
  memset(&sa, 0, sizeof(sa));
  sa.sa_sigaction = segv_handler;
  sa.sa_flags = SA_NODEFER | SA_SIGINFO;
  sigaction(SIGSEGV, &sa, NULL);
  sigaction(SIGBUS, &sa, NULL);
}

#define NONFAILING(...)                                                \
  {                                                                    \
    __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST);               \
    if (_setjmp(segv_env) == 0) {                                      \
      __VA_ARGS__;                                                     \
    }                                                                  \
    __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST);               \
  }

static uintptr_t syz_open_dev(uintptr_t a0, uintptr_t a1, uintptr_t a2)
{
  if (a0 == 0xc || a0 == 0xb) {
    char buf[128];
    sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block",
            (uint8_t)a1, (uint8_t)a2);
    return open(buf, O_RDWR, 0);
  } else {
    char buf[1024];
    char* hash;
    strncpy(buf, (char*)a0, sizeof(buf));
    buf[sizeof(buf) - 1] = 0;
    while ((hash = strchr(buf, '#'))) {
      *hash = '0' + (char)(a1 % 10);
      a1 /= 10;
    }
    return open(buf, a2, 0);
  }
}

static uintptr_t syz_open_pts(uintptr_t a0, uintptr_t a1)
{
  int ptyno = 0;
  if (ioctl(a0, TIOCGPTN, &ptyno))
    return -1;
  char buf[128];
  sprintf(buf, "/dev/pts/%d", ptyno);
  return open(buf, a1, 0);
}

static uintptr_t syz_fuse_mount(uintptr_t a0, uintptr_t a1,
                                uintptr_t a2, uintptr_t a3,
                                uintptr_t a4, uintptr_t a5)
{
  uint64_t target = a0;
  uint64_t mode = a1;
  uint64_t uid = a2;
  uint64_t gid = a3;
  uint64_t maxread = a4;
  uint64_t flags = a5;

  int fd = open("/dev/fuse", O_RDWR);
  if (fd == -1)
    return fd;
  char buf[1024];
  sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd,
          (long)uid, (long)gid, (unsigned)mode & ~3u);
  if (maxread != 0)
    sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread);
  if (mode & 1)
    strcat(buf, ",default_permissions");
  if (mode & 2)
    strcat(buf, ",allow_other");
  syscall(SYS_mount, "", target, "fuse", flags, buf);
  return fd;
}

static uintptr_t syz_fuseblk_mount(uintptr_t a0, uintptr_t a1,
                                   uintptr_t a2, uintptr_t a3,
                                   uintptr_t a4, uintptr_t a5,
                                   uintptr_t a6, uintptr_t a7)
{
  uint64_t target = a0;
  uint64_t blkdev = a1;
  uint64_t mode = a2;
  uint64_t uid = a3;
  uint64_t gid = a4;
  uint64_t maxread = a5;
  uint64_t blksize = a6;
  uint64_t flags = a7;

  int fd = open("/dev/fuse", O_RDWR);
  if (fd == -1)
    return fd;
  if (syscall(SYS_mknodat, AT_FDCWD, blkdev, S_IFBLK, makedev(7, 199)))
    return fd;
  char buf[256];
  sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd,
          (long)uid, (long)gid, (unsigned)mode & ~3u);
  if (maxread != 0)
    sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread);
  if (blksize != 0)
    sprintf(buf + strlen(buf), ",blksize=%ld", (long)blksize);
  if (mode & 1)
    strcat(buf, ",default_permissions");
  if (mode & 2)
    strcat(buf, ",allow_other");
  syscall(SYS_mount, blkdev, target, "fuseblk", flags, buf);
  return fd;
}

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);
  case __NR_syz_test:
    return 0;
  case __NR_syz_open_dev:
    return syz_open_dev(a0, a1, a2);
  case __NR_syz_open_pts:
    return syz_open_pts(a0, a1);
  case __NR_syz_fuse_mount:
    return syz_fuse_mount(a0, a1, a2, a3, a4, a5);
  case __NR_syz_fuseblk_mount:
    return syz_fuseblk_mount(a0, a1, a2, a3, a4, a5, a6, a7);
  }
}

long r[4];

int main()
{
  install_segv_handler();
  memset(r, -1, sizeof(r));
  r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x9bc000ul, 0x3ul,
                         0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
  r[1] = execute_syscall(__NR_socket, 0x10ul, 0x3ul, 0x10ul, 0, 0, 0, 0,
                         0, 0);
  NONFAILING(memcpy((void*)0x2061a000,
                    "\x1f\x00\x00\x00\x24\x00\x07\x83\xf9\xff\xff\xff"
                    "\xff\xff\xff\xff\x03\x00\x09\x0a\x45\x58\xe2\x93"
                    "\x3e\x00\x03\x92\x04\x00\x1c\x18\x08\x00\xf3\x01"
                    "\x97\x68\x1a",
                    39));
  r[3] = execute_syscall(__NR_write, r[1], 0x2061a000ul, 0x27ul, 0, 0,
                         0, 0, 0, 0);
  return 0;
}

^ permalink raw reply	[flat|nested] 9+ messages in thread