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Date:   Mon, 22 Jan 2018 17:43:12 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Al Viro <viro@ZenIV.linux.org.uk>
Cc:     netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 03/10] ip_rt_ioctl(): take copyin to caller
Message-ID: <20180122164312.GC27216@lst.de>
References: <20180118193156.GC13338@ZenIV.linux.org.uk> <20180118193755.19997-1-viro@ZenIV.linux.org.uk> <20180118193755.19997-3-viro@ZenIV.linux.org.uk>
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>  	case SIOCGSTAMP:
> @@ -884,8 +885,12 @@ int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
>  		break;
>  	case SIOCADDRT:
>  	case SIOCDELRT:
> +		if (copy_from_user(&rt, p, sizeof(struct rtentry)))
> +			return -EFAULT;
> +		err = ip_rt_ioctl(net, cmd, &rt);
> +		break;
>  	case SIOCRTMSG:
> -		err = ip_rt_ioctl(net, cmd, (void __user *)arg);
> +		err = -EINVAL;

This looks odd, but ip_rt_ioctl never handled SIOCRTMSG to start with,
so it looks fine.  Might be worth splitting into another prep patch
with a good changelog.

ip_rt_ioctl could also use some additional simplification if it's only
called for SIOCADDRT/SIOCDELRT and lose a level of indentation while
we're at it.

But otherwise this looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>