This bug should have no effect on Linux 3.4. It shouldn’t hurt, but the problem it fixes was introduced in 3.16 or 3.17.
Nadav [email protected] wrote: > From: Nadav Amit <[email protected]> > > 3.4.106-rc1 review patch. If anyone has any objections, please let me know. > > ------------------ > > > commit d29b9d7ed76c0b961603ca692b8a562556a20212 upstream. > > The emulator could reuse an op->type from a previous instruction for some > immediate values. If it mistakenly considers the operands as memory > operands, it will performs a memory read and overwrite op->val. > > Consider for instance the ROR instruction - src2 (the number of times) > would be read from memory instead of being used as immediate. > > Mark every immediate operand as such to avoid this problem. > > Fixes: c44b4c6ab80eef3a9c52c7b3f0c632942e6489aa > Signed-off-by: Nadav Amit <[email protected]> > Signed-off-by: Paolo Bonzini <[email protected]> > Signed-off-by: Zefan Li <[email protected]> > --- > arch/x86/kvm/emulate.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index e125c3e..0a12507 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -3833,6 +3833,7 @@ static int decode_operand(struct x86_emulate_ctxt > *ctxt, struct operand *op, > fetch_register_operand(op); > break; > case OpCL: > + op->type = OP_IMM; > op->bytes = 1; > op->val = ctxt->regs[VCPU_REGS_RCX] & 0xff; > break; > @@ -3840,6 +3841,7 @@ static int decode_operand(struct x86_emulate_ctxt > *ctxt, struct operand *op, > rc = decode_imm(ctxt, op, 1, true); > break; > case OpOne: > + op->type = OP_IMM; > op->bytes = 1; > op->val = 1; > break; > @@ -3879,21 +3881,27 @@ static int decode_operand(struct x86_emulate_ctxt > *ctxt, struct operand *op, > ctxt->memop.bytes = ctxt->op_bytes + 2; > goto mem_common; > case OpES: > + op->type = OP_IMM; > op->val = VCPU_SREG_ES; > break; > case OpCS: > + op->type = OP_IMM; > op->val = VCPU_SREG_CS; > break; > case OpSS: > + op->type = OP_IMM; > op->val = VCPU_SREG_SS; > break; > case OpDS: > + op->type = OP_IMM; > op->val = VCPU_SREG_DS; > break; > case OpFS: > + op->type = OP_IMM; > op->val = VCPU_SREG_FS; > break; > case OpGS: > + op->type = OP_IMM; > op->val = VCPU_SREG_GS; > break; > case OpImplicit: > -- > 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
