linux-kernel - [PATCH 02/18] KVM: Fix overflow bug in overflow detection code

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Date:	Thu, 26 Apr 2007 12:22:02 +0300
From:	Avi Kivity <avi@...ranet.com>
To:	kvm-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org,
	Eric Sesterhenn / Snakebyte <snakebyte@....de>,
	Avi Kivity <avi@...ranet.com>
Subject: [PATCH 02/18] KVM: Fix overflow bug in overflow detection code

From: Eric Sesterhenn / Snakebyte <snakebyte@....de>

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@....de>
Signed-off-by: Avi Kivity <avi@...ranet.com>
---
 drivers/kvm/vmx.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 61a6116..8c0115b 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),
-- 
1.5.0.6

-
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