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From: Dominique Martinet <asmadeus@codewreck.org>
To: Omar Sandoval <osandov@osandov.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Eric Biederman <ebiederm@xmission.com>,
	James Morse <james.morse@arm.com>,
	Bhupesh Sharma <bhsharma@redhat.com>,
	kernel-team@fb.com
Subject: Re: [PATCH] proc/kcore: fix invalid memory access in multi-page read optimization
Date: Wed, 5 Sep 2018 00:24:22 +0200	[thread overview]
Message-ID: <20180904222422.GB17486@nautica> (raw)
In-Reply-To: <20180904180352.GA24406@vader>

Omar Sandoval wrote on Tue, Sep 04, 2018:
> On Wed, Aug 29, 2018 at 06:04:07AM +0200, Dominique Martinet wrote:
> > The 'm' kcore_list item can point to kclist_head, and it is incorrect to
> > look at m->addr / m->size in this case.
> > There is no choice but to run through the list of entries for every address
> > if we did not find any entry in the previous iteration
> > 
> > Fixes: bf991c2231117 ("proc/kcore: optimize multiple page reads")
> > Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
> > ---
> > 
> > I guess now I'm looking at bf991c2231117 again that it would be slightly
> > more efficient to remove the !m check and initialize m to point to
> > kclist_head like this:
> >  m = list_entry(&kclist_head, struct kcore_list, list);
> > but it feels a bit forced to me; deferring the choice to others.
> 
> Good catch! Sorry I missed this last week, Google decided this was spam
> for some reason.

Joys of self-hosted emails, it happens from time to time :/

> How about fixing it like this? One less conditional in the common
> case, no hacky list_entry :)

Good idea, I'll send a v2 in a few minutes after rebooting into it, no
reason it won't work but might as well make earth a slightly warmer
place along the way.

-- 
Dominique

  reply	other threads:[~2018-09-05  2:51 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-18 22:58 [PATCH v3 0/8] /proc/kcore improvements Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 1/8] proc/kcore: don't grab lock for kclist_add() Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 2/8] proc/kcore: don't grab lock for memory hotplug notifier Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 3/8] proc/kcore: replace kclist_lock rwlock with rwsem Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 4/8] proc/kcore: fix memory hotplug vs multiple opens race Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 5/8] proc/kcore: hold lock during read Omar Sandoval
2018-07-24 15:11   ` Tetsuo Handa
2018-07-25 23:34     ` Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 6/8] proc/kcore: clean up ELF header generation Omar Sandoval
2018-07-18 22:58 ` [PATCH v3 7/8] proc/kcore: optimize multiple page reads Omar Sandoval
2018-08-28 10:59   ` KASAN error in " Dominique Martinet
2018-08-29  4:04     ` [PATCH] proc/kcore: fix invalid memory access in multi-page read optimization Dominique Martinet
2018-09-04 18:03       ` Omar Sandoval
2018-09-04 22:24         ` Dominique Martinet [this message]
2018-09-04 22:35       ` [PATCH v2] " Dominique Martinet
2018-09-04 22:38         ` [PATCH v3] " Dominique Martinet
2018-09-04 22:41           ` Omar Sandoval
2018-09-05 19:56             ` Bhupesh Sharma
2018-09-05 20:57           ` Andrew Morton
2018-09-05 22:00             ` Dominique Martinet
2018-07-18 22:58 ` [PATCH v3 8/8] proc/kcore: add vmcoreinfo note to /proc/kcore Omar Sandoval

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