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From: David Laight <David.Laight@ACULAB.COM>
To: 'Jakub Kicinski' <kuba@kernel.org>, Peter Collingbourne <pcc@google.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Colin Ian King <colin.king@canonical.com>,
	Cong Wang <cong.wang@bytedance.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Greg KH <gregkh@linuxfoundation.org>,
	"Arnd Bergmann" <arnd@kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: RE: [PATCH v2] net: don't unconditionally copy_from_user a struct ifreq for socket ioctls
Date: Wed, 1 Sep 2021 08:22:42 +0000	[thread overview]
Message-ID: <bf0f47974d7141358d810d512d4b9a00@AcuMS.aculab.com> (raw)
In-Reply-To: <20210831093006.6db30672@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

From: Jakub Kicinski
> Sent: 31 August 2021 17:30
> 
> On Thu, 26 Aug 2021 12:46:01 -0700 Peter Collingbourne wrote:
> > @@ -3306,6 +3308,8 @@ static int compat_ifr_data_ioctl(struct net *net, unsigned int cmd,
> >  	struct ifreq ifreq;
> >  	u32 data32;
> >
> > +	if (!is_socket_ioctl_cmd(cmd))
> > +		return -ENOTTY;
> >  	if (copy_from_user(ifreq.ifr_name, u_ifreq32->ifr_name, IFNAMSIZ))
> >  		return -EFAULT;
> >  	if (get_user(data32, &u_ifreq32->ifr_data))
> 
> Hi Peter, when resolving the net -> net-next merge conflict I couldn't
> figure out why this chunk is needed. It seems all callers of
> compat_ifr_data_ioctl() already made sure it's a socket IOCTL.
> Please double check my resolution (tip of net-next) and if this is
> indeed unnecessary perhaps send a cleanup? Thanks!

To stop the copy_from_user() faulting when the user buffer
isn't long enough.
In particular for iasatty() on arm with tagged pointers.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)


  reply	other threads:[~2021-09-01  8:22 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26 19:46 Peter Collingbourne
2021-08-27  8:50 ` patchwork-bot+netdevbpf
2021-08-31 16:30 ` Jakub Kicinski
2021-09-01  8:22   ` David Laight [this message]
2021-09-01 14:03     ` Jakub Kicinski
2021-09-01 18:01       ` Peter Collingbourne
2021-09-01 23:20         ` Jakub Kicinski

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