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* kvm: use-after-free in kvm_irqfd_release
@ 2016-06-21 13:19 Dmitry Vyukov
  0 siblings, 0 replies; only message in thread
From: Dmitry Vyukov @ 2016-06-21 13:19 UTC (permalink / raw)
  To: Paolo Bonzini, mtosatti, yoshikawa_takuya_b1, guangrong.xiao,
	Steve Rutherford, rkrcmar, KVM list, LKML
  Cc: syzkaller, Alexander Potapenko, Kostya Serebryany, Sasha Levin

Hello,

The following program triggers use-after-free in kvm_irqfd_release:

BUG: KASAN: use-after-free in do_raw_spin_lock+0x281/0x2b0 at addr
ffff880060888c64
Read of size 4 by task a.out/7084
page:ffffea0001822200 count:0 mapcount:-127 mapping:          (null) index:0x0
flags: 0x4fffe0000000000()
page dumped because: kasan: bad access detected
CPU: 2 PID: 7084 Comm: a.out Tainted: G      D         4.7.0-rc4+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 ffffffff880b58e0 ffff880060b77b78 ffffffff82cc62cf ffffffff60b77c08
 fffffbfff1016b1c ffff880060b77c08 ffff880060888c64 ffff880060888c98
 ffff88003ad2d6a8 ffff880060888c60 ffff880060b77bf8 ffffffff817bdfb2
Call Trace:
 [<ffffffff817be09e>] __asan_report_load4_noabort+0x3e/0x40
mm/kasan/report.c:318
 [<     inline     >] debug_spin_lock_before kernel/locking/spinlock_debug.c:83
 [<ffffffff81484e81>] do_raw_spin_lock+0x281/0x2b0
kernel/locking/spinlock_debug.c:135
 [<     inline     >] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:131
 [<ffffffff86a969df>] _raw_spin_lock_irq+0x6f/0x80 kernel/locking/spinlock.c:167
 [<     inline     >] spin_lock_irq include/linux/spinlock.h:332
 [<ffffffff81073eff>] kvm_irqfd_release+0x2f/0x120
arch/x86/kvm/../../../virt/kvm/eventfd.c:584
 [<ffffffff8105dfca>] kvm_vm_release+0x3a/0x50
arch/x86/kvm/../../../virt/kvm/kvm_main.c:752
 [<ffffffff81819ee6>] __fput+0x236/0x780 fs/file_table.c:208
 [<ffffffff8181a4b5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff813d0826>] task_work_run+0xf6/0x170 kernel/task_work.c:115
 [<     inline     >] exit_task_work include/linux/task_work.h:21
 [<ffffffff8137aed2>] do_exit+0xa62/0x2c80 kernel/exit.c:748
 [<     inline     >] SYSC_exit kernel/exit.c:847
 [<ffffffff8137d152>] SyS_exit+0x22/0x30 kernel/exit.c:845
 [<ffffffff86a96fc0>] entry_SYSCALL_64_fastpath+0x23/0xc1
arch/x86/entry/entry_64.S:207
Memory state around the buggy address:
 ffff880060888b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff880060888b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff880060888c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                       ^
 ffff880060888c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff880060888d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
BUG: unable to handle kernel paging request at ffff880060888c64
IP: [<     inline     >] debug_spin_lock_before
kernel/locking/spinlock_debug.c:83
IP: [<ffffffff81484c3e>] do_raw_spin_lock+0x3e/0x2b0
kernel/locking/spinlock_debug.c:135
PGD a3bc067 PUD a3bf067 PMD 7fdfc067 PTE 8000000060888060
Oops: 0000 [#2] SMP DEBUG_PAGEALLOC KASAN
Modules linked in:
CPU: 2 PID: 7084 Comm: a.out Tainted: G    B D         4.7.0-rc4+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
task: ffff880060a517c0 ti: ffff880060b70000 task.ti: ffff880060b70000
RIP: 0010:[<ffffffff81484c3e>]  [<ffffffff81484c3e>] do_raw_spin_lock+0x3e/0x2b0
RSP: 0018:ffff880060b77c40  EFLAGS: 00010092
RAX: ffff880060a517c0 RBX: ffff880060888c60 RCX: 0000000000000000
RDX: 0000000000000004 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffff880060b77c68 R08: 0000000000000001 R09: 0000000000000000
R10: ffff880060b77bce R11: 0000000000000000 R12: ffff880063813174
R13: ffff880060888c98 R14: ffff88003ad2d6a8 R15: ffff880060888c60
FS:  00007f34165a4700(0000) GS:ffff88006d400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff880060888c64 CR3: 0000000060013000 CR4: 00000000000026e0
Stack:
 ffff880060888c60 ffff880063813174 ffff880060888c98 ffff88003ad2d6a8
 ffff880060888c60 ffff880060b77c88 ffffffff86a969df ffffffff81073eff
 ffff880060888000 ffff880060b77cc8 ffffffff81073eff 00000000000000c0
Call Trace:
 [<     inline     >] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:131
 [<ffffffff86a969df>] _raw_spin_lock_irq+0x6f/0x80 kernel/locking/spinlock.c:167
 [<     inline     >] spin_lock_irq include/linux/spinlock.h:332
 [<ffffffff81073eff>] kvm_irqfd_release+0x2f/0x120
arch/x86/kvm/../../../virt/kvm/eventfd.c:584
 [<ffffffff8105dfca>] kvm_vm_release+0x3a/0x50
arch/x86/kvm/../../../virt/kvm/kvm_main.c:752
 [<ffffffff81819ee6>] __fput+0x236/0x780 fs/file_table.c:208
 [<ffffffff8181a4b5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff813d0826>] task_work_run+0xf6/0x170 kernel/task_work.c:115
 [<     inline     >] exit_task_work include/linux/task_work.h:21
 [<ffffffff8137aed2>] do_exit+0xa62/0x2c80 kernel/exit.c:748
 [<     inline     >] SYSC_exit kernel/exit.c:847
 [<ffffffff8137d152>] SyS_exit+0x22/0x30 kernel/exit.c:845
 [<ffffffff86a96fc0>] entry_SYSCALL_64_fastpath+0x23/0xc1
arch/x86/entry/entry_64.S:207
Code: 55 41 54 53 48 89 fb 48 83 c7 04 48 89 fa 48 c1 ea 03 0f b6 14
02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 3e 02 00 00 <81>
7b 04 ad 4e ad de 0f 85 b9 01 00 00 4c 8d 63 10 48 b8 00 00
RIP  [<     inline     >] debug_spin_lock_before
kernel/locking/spinlock_debug.c:83
RIP  [<ffffffff81484c3e>] do_raw_spin_lock+0x3e/0x2b0
kernel/locking/spinlock_debug.c:135
 RSP <ffff880060b77c40>
CR2: ffff880060888c64
---[ end trace 423f749510e6178a ]---
Fixing recursive fault but reboot is needed!
BUG: scheduling while atomic: a.out/7084/0x00000002
lockdep is turned off.
Modules linked in:
irq event stamp: 0
hardirqs last  enabled at (0): [<          (null)>]           (null)
hardirqs last disabled at (0): [<ffffffff813664cd>]
copy_process.part.38+0x11dd/0x5b20 kernel/fork.c:1428
softirqs last  enabled at (0): [<ffffffff8136656e>]
copy_process.part.38+0x127e/0x5b20 kernel/fork.c:1431
softirqs last disabled at (0): [<          (null)>]           (null)
CPU: 2 PID: 7084 Comm: a.out Tainted: G    B D         4.7.0-rc4+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 ffffffff880b58e0 ffff880060b776d8 ffffffff82cc62cf ffffffff60a517c0
 fffffbfff1016b1c ffff880060a517c0 0000000000000002 ffff880060b70000
 0000000000000009 ffff88006d421580 ffff880060b776f8 ffffffff813ee349
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff82cc62cf>] dump_stack+0x12e/0x18f lib/dump_stack.c:51
 [<ffffffff813ee349>] __schedule_bug+0xb9/0xe0 kernel/sched/core.c:3163
 [<     inline     >] schedule_debug kernel/sched/core.c:3178
 [<ffffffff86a8730a>] __schedule+0x128a/0x1ca0 kernel/sched/core.c:3289
 [<ffffffff86a87db7>] schedule+0x97/0x1c0 kernel/sched/core.c:3375
 [<ffffffff8137c230>] do_exit+0x1dc0/0x2c80 kernel/exit.c:698
 [<ffffffff812041c1>] oops_end+0xa1/0xd0 arch/x86/kernel/dumpstack.c:252
 [<ffffffff8128fa51>] no_context+0x2d1/0x8f0 arch/x86/mm/fault.c:795
 [<ffffffff8129026c>] __bad_area_nosemaphore+0x1fc/0x3e0 arch/x86/mm/fault.c:881
 [<ffffffff81290483>] bad_area_nosemaphore+0x33/0x40 arch/x86/mm/fault.c:888
 [<ffffffff81290ca3>] __do_page_fault+0x193/0xbb0 arch/x86/mm/fault.c:1298
 [<ffffffff8129180f>] trace_do_page_fault+0xdf/0x5b0 arch/x86/mm/fault.c:1449
 [<ffffffff81281c14>] do_async_page_fault+0x14/0xd0 arch/x86/kernel/kvm.c:265
 [<ffffffff86a99178>] async_page_fault+0x28/0x30 arch/x86/entry/entry_64.S:923
 [<     inline     >] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:131
 [<ffffffff86a969df>] _raw_spin_lock_irq+0x6f/0x80 kernel/locking/spinlock.c:167
 [<     inline     >] spin_lock_irq include/linux/spinlock.h:332
 [<ffffffff81073eff>] kvm_irqfd_release+0x2f/0x120
arch/x86/kvm/../../../virt/kvm/eventfd.c:584
 [<ffffffff8105dfca>] kvm_vm_release+0x3a/0x50
arch/x86/kvm/../../../virt/kvm/kvm_main.c:752
 [<ffffffff81819ee6>] __fput+0x236/0x780 fs/file_table.c:208
 [<ffffffff8181a4b5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff813d0826>] task_work_run+0xf6/0x170 kernel/task_work.c:115
 [<     inline     >] exit_task_work include/linux/task_work.h:21
 [<ffffffff8137aed2>] do_exit+0xa62/0x2c80 kernel/exit.c:748
 [<     inline     >] SYSC_exit kernel/exit.c:847
 [<ffffffff8137d152>] SyS_exit+0x22/0x30 kernel/exit.c:845
 [<ffffffff86a96fc0>] entry_SYSCALL_64_fastpath+0x23/0xc1
arch/x86/entry/entry_64.S:207


Run in a parallel loop:

// autogenerated by syzkaller (http://github.com/google/syzkaller)
#include <pthread.h>
#include <stdint.h>
#include <string.h>
#include <sys/syscall.h>
#include <unistd.h>

long r[9];

void* thr(void* arg)
{
  switch ((long)arg) {
  case 0:
    r[0] = syscall(SYS_mmap, 0x20000000ul, 0x16000ul, 0x3ul, 0x32ul,
                   0xfffffffffffffffful, 0x0ul);
    break;
  case 1:
    r[2] = syscall(SYS_open, "/dev/kvm", 0x540ul, 0, 0, 0);
    break;
  case 2:
    r[3] = syscall(SYS_ioctl, r[2], 0xae01ul, 0x0ul, 0, 0, 0);
    break;
  case 3:
    r[4] = syscall(SYS_ioctl, r[3], 0xae41ul, 0x1ul, 0, 0, 0);
    break;
  case 4:
    r[5] = syscall(SYS_ioctl, r[4], 0xae80ul, 0, 0, 0, 0);
    break;
  case 5:
    r[6] = syscall(SYS_ioctl, r[4], 0xae80ul, 0, 0, 0, 0);
    break;
  case 6:
    r[7] = syscall(SYS_ioctl, r[4], 0xae80ul, 0, 0, 0, 0);
    break;
  case 7:
    r[8] =
        syscall(SYS_ioctl, r[4], 0x8040ae9ful, 0x20014fe4ul, 0, 0, 0);
    break;
  }
  return 0;
}

int main()
{
  long i;
  pthread_t th[8];

  syscall(SYS_mmap, 0x20000000ul, 0x16000ul, 0x3ul, 0x32ul,
                   0xfffffffffffffffful, 0x0ul);

  srand(getpid());
  memset(r, -1, sizeof(r));
  for (i = 0; i < 8; i++) {
    pthread_create(&th[i], 0, thr, (void*)i);
  }
  for (i = 0; i < 8; i++) {
    pthread_join(th[i], 0);
  }
  for (i = 0; i < 8; i++) {
    pthread_create(&th[i], 0, thr, (void*)i);
    if ((rand() % 2) == 0)
      usleep(rand() % 10000);
  }
  for (i = 0; i < 8; i++) {
    pthread_join(th[i], 0);
  }
  return 0;
}


On commit 67016f6cdfd079e632bbc49e33178b2d558c120a (Jun 20).

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