From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH v2] socket: fix struct ifreq size in compat ioctl
Date: Thu, 13 Sep 2018 16:01:55 -0700 (PDT)
Message-ID: <20180913.160155.409568197887579582.davem@davemloft.net>
References: <20180913124055.14082-1-johannes@sipsolutions.net>
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Cc: netdev@vger.kernel.org, robert@ocallahan.org,
        viro@zeniv.linux.org.uk, johannes.berg@intel.com
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From: Johannes Berg <johannes@sipsolutions.net>
Date: Thu, 13 Sep 2018 14:40:55 +0200

> From: Johannes Berg <johannes.berg@intel.com>
> 
> As reported by Reobert O'Callahan, since Viro's commit to kill
> dev_ifsioc() we attempt to copy too much data in compat mode,
> which may lead to EFAULT when the 32-bit version of struct ifreq
> sits at/near the end of a page boundary, and the next page isn't
> mapped.
> 
> Fix this by passing the approprate compat/non-compat size to copy
> and using that, as before the dev_ifsioc() removal. This works
> because only the embedded "struct ifmap" has different size, and
> this is only used in SIOCGIFMAP/SIOCSIFMAP which has a different
> handler. All other parts of the union are naturally compatible.
> 
> This fixes https://bugzilla.kernel.org/show_bug.cgi?id=199469.
> 
> Fixes: bf4405737f9f ("kill dev_ifsioc()")
> Reported-by: Robert O'Callahan <robert@ocallahan.org>
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Applied and queued up for -stable, thanks Johannes.