From 5045b468037dfe1c848827ce10e99d87f5669160 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 15 May 2014 18:09:29 +0200 Subject: [PATCH] KVM: x86: check CS.DPL against RPL during task switch Table 7-1 of the SDM mentions a check that the code segment's DPL must match the selector's RPL. This was not done by KVM, fix it. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/emulate.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 47e716ef46b7..2fa7ab069817 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1411,7 +1411,7 @@ static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt, /* Does not support long mode */ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, - u16 selector, int seg, u8 cpl) + u16 selector, int seg, u8 cpl, bool in_task_switch) { struct desc_struct seg_desc, old_desc; u8 dpl, rpl; @@ -1486,6 +1486,9 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt, goto exception; break; case VCPU_SREG_CS: + if (in_task_switch && rpl != dpl) + goto exception; + if (!(seg_desc.type & 8)) goto exception; @@ -1547,7 +1550,7 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt, u16 selector, int seg) { u8 cpl = ctxt->ops->cpl(ctxt); - return __load_segment_descriptor(ctxt, selector, seg, cpl); + return __load_segment_descriptor(ctxt, selector, seg, cpl, false); } static void write_register_operand(struct operand *op) @@ -2440,19 +2443,19 @@ static int load_state_from_tss16(struct x86_emulate_ctxt *ctxt, * Now load segment descriptors. If fault happens at this stage * it is handled in a context of new task */ - ret = __load_segment_descriptor(ctxt, tss->ldt, VCPU_SREG_LDTR, cpl); + ret = __load_segment_descriptor(ctxt, tss->ldt, VCPU_SREG_LDTR, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl); + ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl); + ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl); + ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl); + ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; @@ -2577,25 +2580,25 @@ static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt, * Now load segment descriptors. If fault happenes at this stage * it is handled in a context of new task */ - ret = __load_segment_descriptor(ctxt, tss->ldt_selector, VCPU_SREG_LDTR, cpl); + ret = __load_segment_descriptor(ctxt, tss->ldt_selector, VCPU_SREG_LDTR, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl); + ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl); + ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl); + ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl); + ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->fs, VCPU_SREG_FS, cpl); + ret = __load_segment_descriptor(ctxt, tss->fs, VCPU_SREG_FS, cpl, true); if (ret != X86EMUL_CONTINUE) return ret; - ret = __load_segment_descriptor(ctxt, tss->gs, VCPU_SREG_GS, cpl); + ret = __load_segment_descriptor(ctxt, tss->gs, VCPU_SREG_GS, cpl, true); if (ret != X86EMUL_CONTINUE) return ret;