linux-kernel - Re: [PATCH 2/2] vhost: Fix the calculation in vhost

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Message-ID: <e2d68906-ffa1-4e87-4251-d83ce96a8869@redhat.com>
Date:   Mon, 19 Jul 2021 11:30:43 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Xie Yongji <xieyongji@...edance.com>, mst@...hat.com,
        dan.carpenter@...cle.com
Cc:     virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] vhost: Fix the calculation in vhost_overflow()


在 2021/7/16 下午6:22, Xie Yongji 写道:
> This fixes the incorrect calculation for integer overflow
> when the last address of iova range is 0xffffffff.
>
> Fixes: ec33d031a14b ("vhost: detect 32 bit integer wrap around“)
> Reported-by: Jason Wang <jasowang@...hat.com>
> Signed-off-by: Xie Yongji <xieyongji@...edance.com>
> ---
>   drivers/vhost/vhost.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index b9e853e6094d..a9fd1b311d2f 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -738,7 +738,8 @@ static bool log_access_ok(void __user *log_base, u64 addr, unsigned long sz)
>   static bool vhost_overflow(u64 uaddr, u64 size)
>   {
>   	/* Make sure 64 bit math will not overflow. */
> -	return uaddr > ULONG_MAX || size > ULONG_MAX || uaddr > ULONG_MAX - size;
> +	return uaddr > ULONG_MAX || size > ULONG_MAX ||
> +	       uaddr - 1 > ULONG_MAX - size;
>   }


Acked-by: Jason Wang <jasowang@...hat.com>


>   
>   /* Caller should have vq mutex and device mutex. */