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  1. 02 Dec, 2016 4 commits
    • Radim Krčmář's avatar
      KVM: x86: drop error recovery in em_jmp_far and em_ret_far · 39b65301
      Radim Krčmář authored 
      commit 2117d539 upstream.

em_jmp_far and em_ret_far assumed that setting IP can only fail in 64
bit mode, but syzkaller proved otherwise (and SDM agrees).
Code segment was restored upon failure, but it was left uninitialized
outside of long mode, which could lead to a leak of host kernel stack.
We could have fixed that by always saving and restoring the CS, but we
take a simpler approach and just break any guest that manages to fail
as the error recovery is error-prone and modern CPUs don't need emulator
for this.

Found by syzkaller:

  WARNING: CPU: 2 PID: 3668 at arch/x86/kvm/emulate.c:2217 em_ret_far+0x428/0x480
  Kernel panic - not syncing: panic_on_warn set ...

  CPU: 2 PID: 3668 Comm: syz-executor Not tainted 4.9.0-rc4+ #49
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
   [...]
  Call Trace:
   [...] __dump_stack lib/dump_stack.c:15
   [...] dump_stack+0xb3/0x118 lib/dump_stack.c:51
   [...] panic+0x1b7/0x3a3 kernel/panic.c:179
   [...] __warn+0x1c4/0x1e0 kernel/panic.c:542
   [...] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
   [...] em_ret_far+0x428/0x480 arch/x86/kvm/emulate.c:2217
   [...] em_ret_far_imm+0x17/0x70 arch/x86/kvm/emulate.c:2227
   [...] x86_emulate_insn+0x87a/0x3730 arch/x86/kvm/emulate.c:5294
   [...] x86_emulate_instruction+0x520/0x1ba0 arch/x86/kvm/x86.c:5545
   [...] emulate_instruction arch/x86/include/asm/kvm_host.h:1116
   [...] complete_emulated_io arch/x86/kvm/x86.c:6870
   [...] complete_emulated_mmio+0x4e9/0x710 arch/x86/kvm/x86.c:6934
   [...] kvm_arch_vcpu_ioctl_run+0x3b7a/0x5a90 arch/x86/kvm/x86.c:6978
   [...] kvm_vcpu_ioctl+0x61e/0xdd0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2557
   [...] vfs_ioctl fs/ioctl.c:43
   [...] do_vfs_ioctl+0x18c/0x1040 fs/ioctl.c:679
   [...] SYSC_ioctl fs/ioctl.c:694
   [...] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
   [...] entry_SYSCALL_64_fastpath+0x1f/0xc2
Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
Fixes: d1442d85 ("KVM: x86: Handle errors when RIP is set during far jumps")
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      39b65301
    • Radim Krčmář's avatar
      KVM: x86: fix out-of-bounds access in lapic · 3c22c813
      Radim Krčmář authored 
      commit 444fdad8 upstream.

Cluster xAPIC delivery incorrectly assumed that dest_id <= 0xff.
With enabled KVM_X2APIC_API_USE_32BIT_IDS in KVM_CAP_X2APIC_API, a
userspace can send an interrupt with dest_id that results in
out-of-bounds access.

Found by syzkaller:

  BUG: KASAN: slab-out-of-bounds in kvm_irq_delivery_to_apic_fast+0x11fa/0x1210 at addr ffff88003d9ca750
  Read of size 8 by task syz-executor/22923
  CPU: 0 PID: 22923 Comm: syz-executor Not tainted 4.9.0-rc4+ #49
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
   [...]
  Call Trace:
   [...] __dump_stack lib/dump_stack.c:15
   [...] dump_stack+0xb3/0x118 lib/dump_stack.c:51
   [...] kasan_object_err+0x1c/0x70 mm/kasan/report.c:156
   [...] print_address_description mm/kasan/report.c:194
   [...] kasan_report_error mm/kasan/report.c:283
   [...] kasan_report+0x231/0x500 mm/kasan/report.c:303
   [...] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:329
   [...] kvm_irq_delivery_to_apic_fast+0x11fa/0x1210 arch/x86/kvm/lapic.c:824
   [...] kvm_irq_delivery_to_apic+0x132/0x9a0 arch/x86/kvm/irq_comm.c:72
   [...] kvm_set_msi+0x111/0x160 arch/x86/kvm/irq_comm.c:157
   [...] kvm_send_userspace_msi+0x201/0x280 arch/x86/kvm/../../../virt/kvm/irqchip.c:74
   [...] kvm_vm_ioctl+0xba5/0x1670 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3015
   [...] vfs_ioctl fs/ioctl.c:43
   [...] do_vfs_ioctl+0x18c/0x1040 fs/ioctl.c:679
   [...] SYSC_ioctl fs/ioctl.c:694
   [...] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
   [...] entry_SYSCALL_64_fastpath+0x1f/0xc2
Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
Fixes: e45115b6 ("KVM: x86: use physical LAPIC array for logical x2APIC")
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3c22c813
    • Ashok Raj's avatar
      iommu/vt-d: Fix IOMMU lookup for SR-IOV Virtual Functions · eb060c1a
      Ashok Raj authored 
      commit 1c387188 upstream.

The VT-d specification (§8.3.3) says:
    ‘Virtual Functions’ of a ‘Physical Function’ are under the scope
    of the same remapping unit as the ‘Physical Function’.

The BIOS is not required to list all the possible VFs in the scope
tables, and arguably *shouldn't* make any attempt to do so, since there
could be a huge number of them.

This has been broken basically for ever — the VF is never going to match
against a specific unit's scope, so it ends up being assigned to the
INCLUDE_ALL IOMMU. Which was always actually correct by coincidence, but
now we're looking at Root-Complex integrated devices with SR-IOV support
it's going to start being wrong.

Fix it to simply use pci_physfn() before doing the lookup for PCI devices.
Signed-off-by: default avatarSainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: default avatarAshok Raj <ashok.raj@intel.com>
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      eb060c1a
    • David Woodhouse's avatar
      iommu/vt-d: Fix PASID table allocation · 8b23f163
      David Woodhouse authored 
      commit 91017044 upstream.

Somehow I ended up with an off-by-three error in calculating the size of
the PASID and PASID State tables, which triggers allocations failures as
those tables unfortunately have to be physically contiguous.

In fact, even the *correct* maximum size of 8MiB is problematic and is
wont to lead to allocation failures. Since I have extracted a promise
that this *will* be fixed in hardware, I'm happy to limit it on the
current hardware to a maximum of 0x20000 PASIDs, which gives us 1MiB
tables — still not ideal, but better than before.

Reported by Mika Kuoppala <mika.kuoppala@linux.intel.com> and also by
Xunlei Pang <xlpang@redhat.com> who submitted a simpler patch to fix
only the allocation (and not the free) to the "correct" limit... which
was still problematic.
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8b23f163
  3. 26 Nov, 2016 36 commits
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