linux-kernel - Re: [PATCH -v2] memdup

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: <adaeix9ff49.fsf@cisco.com>
Date:	Sat, 07 Mar 2009 08:54:14 -0800
From:	Roland Dreier <rdreier@...co.com>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Li Zefan <lizf@...fujitsu.com>, adobriyan@...il.com,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH -v2] memdup_user(): introduce

 > I would like to question the use of the gfp argument here;
 > copy_from_user sleeps, so you can't use GFP_ATOMIC anyway.
 > You can't use GFP_NOFS etc, because the pagefault path will happily do
 > things that are equivalent, if not identical, to GFP_KERNEL.

That's a convincing argument, and furthermore, strndup_user() does not
take a gfp parameter, so interface consistency also argues that the
function prototype should just be

void *memdup_user(const void __user *src, size_t len);

(By the way, the len parameter of strndup_user() is declared as long,
which seems strange, since it matches neither the userspace strndup()
nor the kernel kstrndup(), which both use size_t.  So using size_t for
memdup_user() and possibly fixing strndup_user() to use size_t as well
seems like the sanest thing)

 - R.


--
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/