Commit c49c759f authored Oct 03, 2014 by Nadav Amit Committed by Paolo Bonzini Nov 03, 2014

KVM: x86: Emulator performs code segment checks on read access

When read access is performed using a readable code segment, the "conforming"
and "non-conforming" checks should not be done. As a result, read using
non-conforming readable code segment fails.

This is according to Intel SDM 5.6.1 ("Accessing Data in Code Segments").

The fix is not to perform the "non-conforming" checks if the access is not a
fetch; the relevant checks are already done when loading the segment.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 0e8a0996

arch/x86/kvm/emulate.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -703,8 +703,8 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
		if (size > *max_size)
		goto bad;
		cpl = ctxt->ops->cpl(ctxt);
		if (!(desc.type & 8)) {
		/* data segment */
		if (!fetch) {
		/* data segment or readable code segment */
		if (cpl > desc.dpl)
		goto bad;
		} else if ((desc.type & 8) && !(desc.type & 4)) {

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