From: Arnd Bergmann <arnd@arndb.de>
To: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.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: Wed, 12 Jun 2013 17:06:39 +0200 [thread overview]
Message-ID: <201306121706.39368.arnd@arndb.de> (raw)
In-Reply-To: <1370958858.2286.5.camel@dabdike>
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.
Arnd
next prev parent reply other threads:[~2013-06-12 15:06 UTC|newest]
Thread overview: 12+ 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 11:02 ` Marek Szyprowski
2013-06-11 13:54 ` James Bottomley
2013-06-12 15:06 ` Arnd Bergmann [this message]
2013-06-13 8:51 ` Marek Szyprowski
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
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