diff options
| author | Marios Pomonis <pomonis@google.com> | 2019-12-11 12:47:41 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-02-14 16:31:04 -0500 |
| commit | 113857794697b60391ffc4de71c50ac67233928c (patch) | |
| tree | 841e5c4944c039e45330247ed850bc5a3f5a25e9 /arch | |
| parent | 1c2107a666e063943224b15b8839863e7f2f5176 (diff) | |
KVM: x86: Protect x86_decode_insn from Spectre-v1/L1TF attacks
commit 3c9053a2cae7ba2ba73766a34cea41baa70f57f7 upstream.
This fixes a Spectre-v1/L1TF vulnerability in x86_decode_insn().
kvm_emulate_instruction() (an ancestor of x86_decode_insn()) is an exported
symbol, so KVM should treat it conservatively from a security perspective.
Fixes: 045a282ca415 ("KVM: emulator: implement fninit, fnstsw, fnstcw")
Signed-off-by: Nick Finco <nifi@google.com>
Signed-off-by: Marios Pomonis <pomonis@google.com>
Reviewed-by: Andrew Honig <ahonig@google.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/emulate.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index ff20ef3fd899..c456a9dbade8 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -21,6 +21,7 @@ */ #include <linux/kvm_host.h> +#include <linux/nospec.h> #include "kvm_cache_regs.h" #include <asm/kvm_emulate.h> #include <linux/stringify.h> @@ -5158,10 +5159,15 @@ done_prefixes: } break; case Escape: - if (ctxt->modrm > 0xbf) - opcode = opcode.u.esc->high[ctxt->modrm - 0xc0]; - else + if (ctxt->modrm > 0xbf) { + size_t size = ARRAY_SIZE(opcode.u.esc->high); + u32 index = array_index_nospec( + ctxt->modrm - 0xc0, size); + + opcode = opcode.u.esc->high[index]; + } else { opcode = opcode.u.esc->op[(ctxt->modrm >> 3) & 7]; + } break; case InstrDual: if ((ctxt->modrm >> 6) == 3) |