diff options
| author | Steve Rutherford <srutherford@google.com> | 2017-01-11 18:28:29 -0800 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2017-06-17 15:45:33 +0200 |
| commit | e11a5f0cc74c8b0f8add083aea0535cf66681a1b (patch) | |
| tree | bcad580e23226e22b25219fcdd58f42fbd6de66c /arch | |
| parent | 3b06d33775a7a2317b286bcde3eb264be053abc3 (diff) | |
KVM: x86: Introduce segmented_write_std
commit 129a72a0d3c8e139a04512325384fe5ac119e74d upstream.
Introduces segemented_write_std.
Switches from emulated reads/writes to standard read/writes in fxsave,
fxrstor, sgdt, and sidt. This fixes CVE-2017-2584, a longstanding
kernel memory leak.
Since commit 283c95d0e389 ("KVM: x86: emulate FXSAVE and FXRSTOR",
2016-11-09), which is luckily not yet in any final release, this would
also be an exploitable kernel memory *write*!
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Fixes: 96051572c819194c37a8367624b285be10297eca
Fixes: 283c95d0e3891b64087706b344a4b545d04a6e62
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Steve Rutherford <srutherford@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/emulate.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 364f020a5..c96485054 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -906,6 +906,20 @@ static int segmented_read_std(struct x86_emulate_ctxt *ctxt, return ctxt->ops->read_std(ctxt, linear, data, size, &ctxt->exception); } +static int segmented_write_std(struct x86_emulate_ctxt *ctxt, + struct segmented_address addr, + void *data, + unsigned int size) +{ + int rc; + ulong linear; + + rc = linearize(ctxt, addr, size, true, &linear); + if (rc != X86EMUL_CONTINUE) + return rc; + return ctxt->ops->write_std(ctxt, linear, data, size, &ctxt->exception); +} + /* * Fetch the next byte of the instruction being emulated which is pointed to * by ctxt->_eip, then increment ctxt->_eip. @@ -3361,8 +3375,8 @@ static int emulate_store_desc_ptr(struct x86_emulate_ctxt *ctxt, } /* Disable writeback. */ ctxt->dst.type = OP_NONE; - return segmented_write(ctxt, ctxt->dst.addr.mem, - &desc_ptr, 2 + ctxt->op_bytes); + return segmented_write_std(ctxt, ctxt->dst.addr.mem, + &desc_ptr, 2 + ctxt->op_bytes); } static int em_sgdt(struct x86_emulate_ctxt *ctxt) |