linux-toradex.git/arch/x86/kvm, branch v3.4.78

KVM: x86: Convert vapic synchronization to _cached functions (CVE-2013-6368)

2014-01-29T13:10:42+00:00

commit fda4e2e85589191b123d31cdc21fd33ee70f50fd upstream.

In kvm_lapic_sync_from_vapic and kvm_lapic_sync_to_vapic there is the
potential to corrupt kernel memory if userspace provides an address that
is at the end of a page.  This patches concerts those functions to use
kvm_write_guest_cached and kvm_read_guest_cached.  It also checks the
vapic_address specified by userspace during ioctl processing and returns
an error to userspace if the address is not a valid GPA.

This is generally not guest triggerable, because the required write is
done by firmware that runs before the guest.  Also, it only affects AMD
processors and oldish Intel that do not have the FlexPriority feature
(unless you disable FlexPriority, of course; then newer processors are
also affected).

Fixes: b93463aa59d6 ('KVM: Accelerated apic support')

Reported-by: Andrew Honig 
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Honig 
Signed-off-by: Paolo Bonzini 
[ lizf: backported to 3.4: based on Paolo's backport hints for <3.10 ]
Signed-off-by: Li Zefan 
Signed-off-by: Greg Kroah-Hartman

Revert "KVM: X86 emulator: fix source operand decoding for 8bit mov[zs]x instructions"

2013-09-14T13:02:11+00:00

This reverts commit 5b5b30580218eae22609989546bac6e44d0eda6e, which was
commit 660696d1d16a71e15549ce1bf74953be1592bcd3 upstream.

Paul Gortmaker  writes:

[this patch] introduces the following:

arch/x86/kvm/emulate.c: In function ‘decode_operand’:
arch/x86/kvm/emulate.c:3974:4: warning: passing argument 1 of ‘decode_register’ makes integer from pointer
+without a cast [enabled by default]
arch/x86/kvm/emulate.c:789:14: note: expected ‘u8’ but argument is of type ‘struct x86_emulate_ctxt *’
arch/x86/kvm/emulate.c:3974:4: warning: passing argument 2 of ‘decode_register’ makes pointer from integer
+without a cast [enabled by default]
arch/x86/kvm/emulate.c:789:14: note: expected ‘long unsigned int *’ but argument is of type ‘u8’

Based on the severity of the warnings above, I'm reasonably sure there will
be some kind of runtime regressions due to this, but I stopped to investigate
the warnings as soon as I saw them, before any run time testing.

It happens because mainline v3.7-rc1~113^2~40 (dd856efafe60) does this:

-static void *decode_register(u8 modrm_reg, unsigned long *regs,
+static void *decode_register(struct x86_emulate_ctxt *ctxt, u8 modrm_reg,

Since 660696d1d16a71e1 was only applied to stable 3.4, 3.8, and 3.9 -- and
the prerequisite above is in 3.7+, the issue should be limited to 3.4.44+

Reported-by: Paul Gortmaker 
Acked-by: Paolo Bonzini 
Cc: Gleb Natapov 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: remove vcpu's CPL check in host-invoked XCR set

2013-06-27T18:27:30+00:00

commit 764bcbc5a6d7a2f3e75c9f0e4caa984e2926e346 upstream.

__kvm_set_xcr function does the CPL check when set xcr. __kvm_set_xcr is
called in two flows, one is invoked by guest, call stack shown as below,

  handle_xsetbv(or xsetbv_interception)
    kvm_set_xcr
      __kvm_set_xcr

the other one is invoked by host, for example during system reset:

  kvm_arch_vcpu_ioctl
    kvm_vcpu_ioctl_x86_set_xcrs
      __kvm_set_xcr

The former does need the CPL check, but the latter does not.

Signed-off-by: Zhang Haoyu 
[Tweaks to commit message. - Paolo]
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

KVM: VMX: fix halt emulation while emulating invalid guest sate

2013-05-19T17:54:34+00:00

commit 8d76c49e9ffeee839bc0b7a3278a23f99101263e upstream.

The invalid guest state emulation loop does not check halt_request
which causes 100% cpu loop while guest is in halt and in invalid
state, but more serious issue is that this leaves halt_request set, so
random instruction emulated by vm86 #GP exit can be interpreted
as halt which causes guest hang. Fix both problems by handling
halt_request in emulation loop.

Reported-by: Tomas Papan 
Tested-by: Tomas Papan 
Reviewed-by: Paolo Bonzini 
Signed-off-by: Gleb Natapov 
Signed-off-by: Greg Kroah-Hartman

KVM: X86 emulator: fix source operand decoding for 8bit mov[zs]x instructions

2013-05-08T02:51:57+00:00

commit 660696d1d16a71e15549ce1bf74953be1592bcd3 upstream.

Source operand for one byte mov[zs]x is decoded incorrectly if it is in
high byte register. Fix that.

Signed-off-by: Gleb Natapov 
Signed-off-by: Greg Kroah-Hartman

KVM: Allow cross page reads and writes from cached translations.

2013-04-26T04:19:55+00:00

commit 8f964525a121f2ff2df948dac908dcc65be21b5b upstream.

This patch adds support for kvm_gfn_to_hva_cache_init functions for
reads and writes that will cross a page.  If the range falls within
the same memslot, then this will be a fast operation.  If the range
is split between two memslots, then the slower kvm_read_guest and
kvm_write_guest are used.

Tested: Test against kvm_clock unit tests.

Signed-off-by: Andrew Honig 
Signed-off-by: Gleb Natapov 
Cc: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: Convert MSR_KVM_SYSTEM_TIME to use gfn_to_hva_cache functions (CVE-2013-1797)

2013-04-26T04:19:54+00:00

commit 0b79459b482e85cb7426aa7da683a9f2c97aeae1 upstream.

There is a potential use after free issue with the handling of
MSR_KVM_SYSTEM_TIME.  If the guest specifies a GPA in a movable or removable
memory such as frame buffers then KVM might continue to write to that
address even after it's removed via KVM_SET_USER_MEMORY_REGION.  KVM pins
the page in memory so it's unlikely to cause an issue, but if the user
space component re-purposes the memory previously used for the guest, then
the guest will be able to corrupt that memory.

Tested: Tested against kvmclock unit test

Signed-off-by: Andrew Honig 
Signed-off-by: Marcelo Tosatti 
Cc: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: fix for buffer overflow in handling of MSR_KVM_SYSTEM_TIME (CVE-2013-1796)

2013-04-26T04:19:54+00:00

commit c300aa64ddf57d9c5d9c898a64b36877345dd4a9 upstream.

If the guest sets the GPA of the time_page so that the request to update the
time straddles a page then KVM will write onto an incorrect page.  The
write is done byusing kmap atomic to get a pointer to the page for the time
structure and then performing a memcpy to that page starting at an offset
that the guest controls.  Well behaved guests always provide a 32-byte aligned
address, however a malicious guest could use this to corrupt host kernel
memory.

Tested: Tested against kvmclock unit test.

Signed-off-by: Andrew Honig 
Signed-off-by: Marcelo Tosatti 
Cc: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: invalid opcode oops on SET_SREGS with OSXSAVE bit set (CVE-2012-4461)

2012-12-03T19:47:11+00:00

commit 6d1068b3a98519247d8ba4ec85cd40ac136dbdf9 upstream.

On hosts without the XSAVE support unprivileged local user can trigger
oops similar to the one below by setting X86_CR4_OSXSAVE bit in guest
cr4 register using KVM_SET_SREGS ioctl and later issuing KVM_RUN
ioctl.

invalid opcode: 0000 [#2] SMP
Modules linked in: tun ip6table_filter ip6_tables ebtable_nat ebtables
...
Pid: 24935, comm: zoog_kvm_monito Tainted: G      D      3.2.0-3-686-pae
EIP: 0060:[] EFLAGS: 00210246 CPU: 0
EIP is at kvm_arch_vcpu_ioctl_run+0x92a/0xd13 [kvm]
EAX: 00000001 EBX: 000f387e ECX: 00000000 EDX: 00000000
ESI: 00000000 EDI: 00000000 EBP: ef5a0060 ESP: d7c63e70
 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Process zoog_kvm_monito (pid: 24935, ti=d7c62000 task=ed84a0c0
task.ti=d7c62000)
Stack:
 00000001 f70a1200 f8b940a9 ef5a0060 00000000 00200202 f8769009 00000000
 ef5a0060 000f387e eda5c020 8722f9c8 00015bae 00000000 ed84a0c0 ed84a0c0
 c12bf02d 0000ae80 ef7f8740 fffffffb f359b740 ef5a0060 f8b85dc1 0000ae80
Call Trace:
 [] ? kvm_arch_vcpu_ioctl_set_sregs+0x2fe/0x308 [kvm]
...
 [] ? syscall_call+0x7/0xb
Code: 89 e8 e8 14 ee ff ff ba 00 00 04 00 89 e8 e8 98 48 ff ff 85 c0 74
1e 83 7d 48 00 75 18 8b 85 08 07 00 00 31 c9 8b 95 0c 07 00 00 <0f> 01
d1 c7 45 48 01 00 00 00 c7 45 1c 01 00 00 00 0f ae f0 89
EIP: [] kvm_arch_vcpu_ioctl_run+0x92a/0xd13 [kvm] SS:ESP
0068:d7c63e70

QEMU first retrieves the supported features via KVM_GET_SUPPORTED_CPUID
and then sets them later. So guest's X86_FEATURE_XSAVE should be masked
out on hosts without X86_FEATURE_XSAVE, making kvm_set_cr4 with
X86_CR4_OSXSAVE fail. Userspaces that allow specifying guest cpuid with
X86_FEATURE_XSAVE even on hosts that do not support it, might be
susceptible to this attack from inside the guest as well.

Allow setting X86_CR4_OSXSAVE bit only if host has XSAVE support.

Signed-off-by: Petr Matousek 
Signed-off-by: Marcelo Tosatti 
Signed-off-by: Greg Kroah-Hartman

KVM: ensure async PF event wakes up vcpu from halt

2012-05-06T11:56:54+00:00

If vcpu executes hlt instruction while async PF is waiting to be delivered
vcpu can block and deliver async PF only after another even wakes it
up. This happens because kvm_check_async_pf_completion() will remove
completion event from vcpu->async_pf.done before entering kvm_vcpu_block()
and this will make kvm_arch_vcpu_runnable() return false. The solution
is to make vcpu runnable when processing completion.

Signed-off-by: Gleb Natapov 
Signed-off-by: Avi Kivity