From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Michal Simek <michal.simek@xilinx.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Michal Simek <monstr@monstr.eu>,
Linux-Arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH] dma-mapping: Add BUG_ON for uninitialized dma_ops
Date: Thu, 13 Jun 2013 10:51:30 +0200 [thread overview]
Message-ID: <51B98812.80201@samsung.com> (raw)
In-Reply-To: <201306121706.39368.arnd@arndb.de>
On 6/12/2013 5:06 PM, Arnd Bergmann wrote:
> On Tuesday 11 June 2013, James Bottomley wrote:
> > Really, no, it's not a good idea at all. It invites tons of patches
> > littering the code with BUG_ONs where we might possibly get a NULL
> > dereference. All it does is add extra instructions to a code path for
> > no actual benefit.
> >
> > If you can answer the question: what more information does the BUG_ON
> > give you than the NULL deref Oops would not? then it might be
> > reasonable.
>
> The question is if a user can trigger the NULL dereference intentionally,
> in which case they might get the kernel to jump into a user-provided
> buffer.
I don't any possibility for userspace to alter the ops pointer, so if you
think that BUG_ON() approach causes additional overhead then I'm fine to
remove it.
Best regards
--
Marek Szyprowski
Samsung R&D Institute Poland
next prev parent reply other threads:[~2013-06-13 8:51 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-03 12:44 [PATCH] dma-mapping: Add BUG_ON for uninitialized dma_ops Michal Simek
2013-06-10 9:00 ` Michal Simek
2013-06-11 2:34 ` Bjorn Helgaas
2013-06-11 2:34 ` Bjorn Helgaas
2013-06-11 11:02 ` Marek Szyprowski
2013-06-11 11:02 ` Marek Szyprowski
2013-06-11 13:54 ` James Bottomley
2013-06-12 15:06 ` Arnd Bergmann
2013-06-13 8:51 ` Marek Szyprowski [this message]
2013-06-13 20:59 ` James Bottomley
2013-06-14 14:36 ` Arnd Bergmann
2013-06-14 16:14 ` James Bottomley
2013-06-19 15:20 ` Arnd Bergmann
2013-06-26 12:58 ` Michal Simek
2013-06-26 12:58 ` Michal Simek
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