From 56f2b2e46c25cf5321bfde3c05ce8505fc1e9e1a Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 23 Oct 2014 14:54:14 +0200 Subject: KVM: emulate: avoid accessing NULL ctxt->memopp commit a430c9166312e1aa3d80bce32374233bdbfeba32 upstream. 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 Fixes: 41061cdb98a0bec464278b4db8e894a3121671f5 Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/emulate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index 41157106f548..258b0d934994 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -4481,10 +4481,10 @@ done_prefixes: /* 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; } -- cgit v1.2.3