linux-kernel - Re: [PATCH] arm64: __clear_user: handle exceptions on strb

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Message-ID: <20141113151407.GG6869@redacted.bos.redhat.com>
Date:	Thu, 13 Nov 2014 10:14:08 -0500
From:	Kyle McMartin <kmcmarti@...hat.com>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"pmatouse@...hat.com" <pmatouse@...hat.com>,
	Will Deacon <Will.Deacon@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] arm64: __clear_user: handle exceptions on strb

On Thu, Nov 13, 2014 at 03:06:25PM +0000, Catalin Marinas wrote:
> On Wed, Nov 12, 2014 at 09:07:44PM +0000, Kyle McMartin wrote:
> > ARM64 currently doesn't fix up faults on the single-byte (strb) case of
> > __clear_user... which means that we can cause a nasty kernel panic as an
> > ordinary user with any multiple PAGE_SIZE+1 read from /dev/zero.
> > i.e.: dd if=/dev/zero of=foo ibs=1 count=1 (or ibs=65537, etc.)
> 
> Thanks for this, it's been like this for a while. Applied.
> 

Thanks Catalin, if it's not too late, I forgot to add a
Reported-by: Miloš Prchlík <mprchlik@...hat.com>
for the initial report of the panic.

regards, Kyle
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