linux-kernel - Re: Should mmap MAP_LOCKED fail if mm

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]

Date:	Tue, 28 Apr 2015 14:11:48 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	linux-mm@...ck.org
Cc:	Cyril Hrubis <chrubis@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Michel Lespinasse <walken@...gle.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Michael Kerrisk <mtk.manpages@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux API <linux-api@...r.kernel.org>
Subject: Re: Should mmap MAP_LOCKED fail if mm_poppulate fails?

Hi,
it seems that the initial email got lost (or ignored). I would like to
revive it again. I've cooked up a potential fix to this issue which will
follow as a reply to this email.

The first patch is dumb and straightforward. It should be safe as is and
also good without the follow up 2 patches which try to handle potential
allocation failures in the do_munmap path more gracefully. As we still
do not fail small allocations even the first patch could be simplified
a bit and the retry loop replaced by a BUG_ON right away. But I felt this
would better be done robust.

An obvious alternative would be patching the man pages to mention the
subtle difference between mlock and MAP_LOCKED semantic. I have checked
debian code search and it shown some applications relying on MAP_LOCKED
but I have no idea whether they really require the mlock all-or-nothing
fault in semantic.

Any thoughts, ideas?

--
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/