# Re: \[PATCH 2/2\] vhost: Fix the calculation in vhost\_overflow()

- List: virtualization
- 1 message, 1 author
- Page: https://ratatoskr.run/virtualization/2021/07/1448673/t

## Re: \[PATCH 2/2\] vhost: Fix the calculation in vhost\_overflow()

- From: Jason Wang \<hidden\>
- Date: 2021-07-19 03:30:56 
- Message: https://ratatoskr.run/virtualization/2021/07/1448673.md

```text

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 <redacted>
> Signed-off-by: Xie Yongji <redacted>
> ---
>   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 <redacted>


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

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