Commit d9092f52 authored Oct 27, 2016 by Owen Hofmann Committed by Paolo Bonzini Nov 02, 2016

kvm: x86: Check memopp before dereference (CVE-2016-8630)



Commit 41061cdb ("KVM: emulate: do not initialize memopp") removes a
check for non-NULL under incorrect assumptions. An undefined instruction
with a ModR/M byte with Mod=0 and R/M-5 (e.g. 0xc7 0x15) will attempt
to dereference a null pointer here.

Fixes: 41061cdb
Message-Id: <1477592752-126650-2-git-send-email-osh@google.com>
Signed-off-by: Owen Hofmann <osh@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 355f4fb1

arch/x86/kvm/emulate.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5045,7 +5045,7 @@ done_prefixes:
		/* Decode and fetch the destination operand: register or memory. */
		rc = decode_operand(ctxt, &ctxt->dst, (ctxt->d >> DstShift) & OpMask);

		if (ctxt->rip_relative)
		if (ctxt->rip_relative && likely(ctxt->memopp))
		ctxt->memopp->addr.mem.ea = address_mask(ctxt,
		ctxt->memopp->addr.mem.ea + ctxt->_eip);

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