netdev - [PATCH v1] drivers/vhost/vhost: fix overflow checks in vhost

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Message-Id: <20221207134631.907221-1-d-tatianin@yandex-team.ru>
Date:   Wed,  7 Dec 2022 16:46:31 +0300
From:   Daniil Tatianin <d-tatianin@...dex-team.ru>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Daniil Tatianin <d-tatianin@...dex-team.ru>,
        Jason Wang <jasowang@...hat.com>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1] drivers/vhost/vhost: fix overflow checks in vhost_overflow

The if statement would erroneously check for > ULONG_MAX, which could
never evaluate to true. Check for equality instead.

Found by Linux Verification Center (linuxtesting.org) with the SVACE
static analysis tool.

Signed-off-by: Daniil Tatianin <d-tatianin@...dex-team.ru>
---
 drivers/vhost/vhost.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 40097826cff0..8df706e7bc6c 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -730,7 +730,7 @@ static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
 /* Make sure 64 bit math will not overflow. */
 static bool vhost_overflow(u64 uaddr, u64 size)
 {
-	if (uaddr > ULONG_MAX || size > ULONG_MAX)
+	if (uaddr == ULONG_MAX || size == ULONG_MAX)
 		return true;
 
 	if (!size)
-- 
2.25.1