• Radim Krčmář's avatar
    KVM: x86: check for pic and ioapic presence before use · df492896
    Radim Krčmář authored
    Split irqchip allows pic and ioapic routes to be used without them being
    created, which results in NULL access.  Check for NULL and avoid it.
    (The setup is too racy for a nicer solutions.)
    
    Found by syzkaller:
    
      general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN
      Dumping ftrace buffer:
         (ftrace buffer empty)
      Modules linked in:
      CPU: 3 PID: 11923 Comm: kworker/3:2 Not tainted 4.9.0-rc5+ #27
      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
      Workqueue: events irqfd_inject
      task: ffff88006a06c7c0 task.stack: ffff880068638000
      RIP: 0010:[...]  [...] __lock_acquire+0xb35/0x3380 kernel/locking/lockdep.c:3221
      RSP: 0000:ffff88006863ea20  EFLAGS: 00010006
      RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: 0000000000000000
      RDX: 0000000000000039 RSI: 0000000000000000 RDI: 1ffff1000d0c7d9e
      RBP: ffff88006863ef58 R08: 0000000000000001 R09: 0000000000000000
      R10: 00000000000001c8 R11: 0000000000000000 R12: ffff88006a06c7c0
      R13: 0000000000000001 R14: ffffffff8baab1a0 R15: 0000000000000001
      FS:  0000000000000000(0000) GS:ffff88006d100000(0000) knlGS:0000000000000000
      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      CR2: 00000000004abdd0 CR3: 000000003e2f2000 CR4: 00000000000026e0
      Stack:
       ffffffff894d0098 1ffff1000d0c7d56 ffff88006863ecd0 dffffc0000000000
       ffff88006a06c7c0 0000000000000000 ffff88006863ecf8 0000000000000082
       0000000000000000 ffffffff815dd7c1 ffffffff00000000 ffffffff00000000
      Call Trace:
       [...] lock_acquire+0x2a2/0x790 kernel/locking/lockdep.c:3746
       [...] __raw_spin_lock include/linux/spinlock_api_smp.h:144
       [...] _raw_spin_lock+0x38/0x50 kernel/locking/spinlock.c:151
       [...] spin_lock include/linux/spinlock.h:302
       [...] kvm_ioapic_set_irq+0x4c/0x100 arch/x86/kvm/ioapic.c:379
       [...] kvm_set_ioapic_irq+0x8f/0xc0 arch/x86/kvm/irq_comm.c:52
       [...] kvm_set_irq+0x239/0x640 arch/x86/kvm/../../../virt/kvm/irqchip.c:101
       [...] irqfd_inject+0xb4/0x150 arch/x86/kvm/../../../virt/kvm/eventfd.c:60
       [...] process_one_work+0xb40/0x1ba0 kernel/workqueue.c:2096
       [...] worker_thread+0x214/0x18a0 kernel/workqueue.c:2230
       [...] kthread+0x328/0x3e0 kernel/kthread.c:209
       [...] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
    Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
    Cc: stable@vger.kernel.org
    Fixes: 49df6397 ("KVM: x86: Split the APIC from the rest of IRQCHIP.")
    Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
    df492896
irq_comm.c 11.5 KB