Commit a430c916 authored Oct 23, 2014 by Paolo Bonzini

KVM: emulate: avoid accessing NULL ctxt->memopp



A failure to decode the instruction can cause a NULL pointer access.
This is fixed simply by moving the "done" label as close as possible
to the return.

This fixes CVE-2014-8481.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Cc: stable@vger.kernel.org
Fixes: 41061cdb
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 08da44ae

arch/x86/kvm/emulate.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -4580,10 +4580,10 @@ int x86_decode_insn(struct x86_emulate_ctxt ctxt, void insn, int insn_len)
		/* Decode and fetch the destination operand: register or memory. */
		rc = decode_operand(ctxt, &ctxt->dst, (ctxt->d >> DstShift) & OpMask);

		done:
		if (ctxt->rip_relative)
		ctxt->memopp->addr.mem.ea += ctxt->_eip;

		done:
		return (rc != X86EMUL_CONTINUE) ? EMULATION_FAILED : EMULATION_OK;
		}