linux-kernel - Re: [PATCH] dma-mapping: Add BUG_ON for uninitialized dma

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <201306121706.39368.arnd@arndb.de>
Date:	Wed, 12 Jun 2013 17:06:39 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	James Bottomley <James.Bottomley@...senpartnership.com>
Cc:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Michal Simek <michal.simek@...inx.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Michal Simek <monstr@...str.eu>,
	"Linux-Arch" <linux-arch@...r.kernel.org>
Subject: Re: [PATCH] dma-mapping: Add BUG_ON for uninitialized dma_ops

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/