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Tsirkin" To: Daniil Tatianin Cc: Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1] drivers/vhost/vhost: fix overflow checks in vhost_overflow Message-ID: <20221207100028-mutt-send-email-mst@kernel.org> References: <20221207134631.907221-1-d-tatianin@yandex-team.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221207134631.907221-1-d-tatianin@yandex-team.ru> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Dec 07, 2022 at 04:46:31PM +0300, Daniil Tatianin wrote: > 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 It can trigger on a 32 bit system. I'd also expect more analysis of the code flow than "this can not trigger switch to a condition that can" to accompany a patch. > --- > 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