From: Eric Sesterhenn / Snakebyte <snakebyte@gmx.de>
Date: Mon, 9 Apr 2007 14:15:05 +0000 (+0200)
Subject: KVM: Fix overflow bug in overflow detection code
X-Git-Tag: v2.6.22-rc1~1008^2~23
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3964994bb5ba85a3d8b54ae618f7be1cecce916d;p=linux-2.6

KVM: Fix overflow bug in overflow detection code

The expression

   sp - 6 < sp

where sp is a u16 is undefined in C since 'sp - 6' is promoted to int,
and signed overflow is undefined in C.  gcc 4.2 actually warns about it.
Replace with a simpler test.

Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 61a611691e..8c0115b548 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1182,7 +1182,7 @@ static void inject_rmode_irq(struct kvm_vcpu *vcpu, int irq)
 	u16 sp =  vmcs_readl(GUEST_RSP);
 	u32 ss_limit = vmcs_read32(GUEST_SS_LIMIT);
 
-	if (sp > ss_limit || sp - 6 > sp) {
+	if (sp > ss_limit || sp < 6 ) {
 		vcpu_printf(vcpu, "%s: #SS, rsp 0x%lx ss 0x%lx limit 0x%x\n",
 			    __FUNCTION__,
 			    vmcs_readl(GUEST_RSP),