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KVM: x86: emulator: Fix illegal LEA handling

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The emulator mishandles LEA with register source operand. Even though such
LEA is illegal, it can be encoded and fed to CPU. In which case real
hardware throws #UD. The emulator, instead, returns address of
x86_emulate_ctxt._regs. This info leak hurts host's kASLR.

Tell the decoder that illegal LEA is not to be emulated.

Signed-off-by: Michal Luczaj <mhal@rbox.co>
Message-Id: <20220729134801.1120-1-mhal@rbox.co>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Michal Luczaj 2022-07-29 15:48:01 +02:00 committed by Paolo Bonzini
parent 2bc685e633
commit 4ac5b42377
1 changed files with 5 additions and 1 deletions
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6
arch/x86/kvm/emulate.c
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@ -4578,6 +4578,10 @@ static const struct mode_dual mode_dual_63 = {
N, I(DstReg | SrcMem32 | ModRM | Mov, em_movsxd)
};
static const struct instr_dual instr_dual_8d = {
D(DstReg | SrcMem | ModRM | NoAccess), N
};
static const struct opcode opcode_table[256] = {
/* 0x00 - 0x07 */
F6ALU(Lock, em_add),
@ -4634,7 +4638,7 @@ static const struct opcode opcode_table[256] = {
I2bv(DstMem | SrcReg | ModRM | Mov | PageTable, em_mov),
I2bv(DstReg | SrcMem | ModRM | Mov, em_mov),
I(DstMem | SrcNone | ModRM | Mov | PageTable, em_mov_rm_sreg),
D(ModRM | SrcMem | NoAccess | DstReg),
ID(0, &instr_dual_8d),
I(ImplicitOps | SrcMem16 | ModRM, em_mov_sreg_rm),
G(0, group1A),
/* 0x90 - 0x97 */