netdev - Re: [PATCH] netrom: fix copying in user data in nr

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Date:   Thu, 6 Jan 2022 17:52:11 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Christoph Hellwig <hch@....de>, ralf@...ux-mips.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-hams@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH] netrom: fix copying in user data in nr_setsockopt

On Tue, Jan 04, 2022 at 10:21:26AM +0100, Christoph Hellwig wrote:
> This code used to copy in an unsigned long worth of data before
> the sockptr_t conversion, so restore that.
> 
> Fixes: a7b75c5a8c41 ("net: pass a sockptr_t into ->setsockopt")
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>  net/netrom/af_netrom.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
> index 775064cdd0ee4..f1ba7dd3d253d 100644
> --- a/net/netrom/af_netrom.c
> +++ b/net/netrom/af_netrom.c
> @@ -306,7 +306,7 @@ static int nr_setsockopt(struct socket *sock, int level, int optname,
>  	if (optlen < sizeof(unsigned int))
>  		return -EINVAL;
>  
> -	if (copy_from_sockptr(&opt, optval, sizeof(unsigned int)))
> +	if (copy_from_sockptr(&opt, optval, sizeof(unsigned long)))
>  		return -EFAULT;

No this isn't right.  In the original code, it copied an unsigned int.

	if (get_user(opt, (unsigned int __user *)optval))

The fix is to probably to change "opt" to an unsigned int.  I wonder if
I need to update all the integer overflow checks to from:

-	if (opt > ULONG_MAX / HZ)
+	if (opt > UINT_MAX / HZ)

...

Probably no one cares, right?  Ralf?

regards,
dan carpenter