linux-kernel - Re: [PATCH] staging: goldfish: use div64_s64 instead of do

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: <20160201145457.7879d53f@lxorguk.ukuu.org.uk>
Date:	Mon, 1 Feb 2016 14:54:57 +0000
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	gregkh@...uxfoundation.org, Greg Hackmann <ghackmann@...gle.com>,
	Jin Qian <jinqian@...roid.com>,
	Alan Cox <alan@...ux.intel.com>, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] staging: goldfish: use div64_s64 instead of do_div

On Mon, 01 Feb 2016 11:33 +0100
Arnd Bergmann <arnd@...db.de> wrote:

> The goldfish nand driver divides a signed 64-bit number (loff_t)
> in multiple places using the do_div() function. This has always
> been unreliable but now produces a compiler warning (since 4.5-rc1):
> 
> goldfish/goldfish_nand.c: In function 'goldfish_nand_erase':
> goldfish/goldfish_nand.c:107:91: error: comparison of distinct pointer types lacks a cast [-Werror]
> goldfish/goldfish_nand.c: In function 'goldfish_nand_read_oob':
> goldfish/goldfish_nand.c:145:91: error: comparison of distinct pointer types lacks a cast [-Werror]
> 
> This changes the code to the equivalent div_s64{,_rem} that
> works correctly for negative numbers (which we should never
> get here).

We can't get negatives as you say so surely the right fix is a cast or to
fix mtd->writesize ?