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From: Johannes Berg <johannes@sipsolutions.net>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: netdev@vger.kernel.org, Robert O'Callahan <robert@ocallahan.org>
Subject: Re: [PATCH] socket: fix struct ifreq size in compat ioctl
Date: Thu, 13 Sep 2018 14:16:45 +0200	[thread overview]
Message-ID: <1536841005.4160.7.camel@sipsolutions.net> (raw)
In-Reply-To: <20180913121353.GR19965@ZenIV.linux.org.uk>

On Thu, 2018-09-13 at 13:13 +0100, Al Viro wrote:
> On Thu, Sep 13, 2018 at 01:49:09PM +0200, Johannes Berg wrote:
> > 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 whether or not we're doing a compat call and
> > copying the appropriate size in/out, as we did before. 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.
> 
> Might be better to pass explicit size instead of this bool compat...

Yeah, that's a bit better perhaps, I should resend to have the bugzilla
link anyway.

johannes

  reply	other threads:[~2018-09-13 17:26 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-13 11:49 [PATCH] socket: fix struct ifreq size in compat ioctl Johannes Berg
2018-09-13 12:13 ` Al Viro
2018-09-13 12:16   ` Johannes Berg [this message]
2018-09-13 22:48 ` kbuild test robot

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