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| author | Marios Pomonis <pomonis@google.com> | 2019-12-11 23:47:50 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-02-15 00:29:57 +0300 |
| commit | 2b158e93c85fbc5880351e4082a1d1dcbfa6f183 (patch) | |
| tree | fb0d15916774507870a99db2e3844a227c2fdf6e | |
| parent | b9112b448e4e1069c16e4f57474dd4ba1f62ec79 (diff) | |
| download | linux-2b158e93c85fbc5880351e4082a1d1dcbfa6f183.tar.xz | |
KVM: x86: Refactor prefix decoding to prevent Spectre-v1/L1TF attacks
commit 125ffc5e0a56a3eded608dc51e09d5ebf72cf652 upstream.
This fixes Spectre-v1/L1TF vulnerabilities in
vmx_read_guest_seg_selector(), vmx_read_guest_seg_base(),
vmx_read_guest_seg_limit() and vmx_read_guest_seg_ar(). When
invoked from emulation, these functions contain index computations
based on the (attacker-influenced) segment value. Using constants
prevents the attack.
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kvm/emulate.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 6c7847b3aa2d..52e8203bdc42 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -5041,16 +5041,28 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) ctxt->ad_bytes = def_ad_bytes ^ 6; break; case 0x26: /* ES override */ + has_seg_override = true; + ctxt->seg_override = VCPU_SREG_ES; + break; case 0x2e: /* CS override */ + has_seg_override = true; + ctxt->seg_override = VCPU_SREG_CS; + break; case 0x36: /* SS override */ + has_seg_override = true; + ctxt->seg_override = VCPU_SREG_SS; + break; case 0x3e: /* DS override */ has_seg_override = true; - ctxt->seg_override = (ctxt->b >> 3) & 3; + ctxt->seg_override = VCPU_SREG_DS; break; case 0x64: /* FS override */ + has_seg_override = true; + ctxt->seg_override = VCPU_SREG_FS; + break; case 0x65: /* GS override */ has_seg_override = true; - ctxt->seg_override = ctxt->b & 7; + ctxt->seg_override = VCPU_SREG_GS; break; case 0x40 ... 0x4f: /* REX */ if (mode != X86EMUL_MODE_PROT64) |