linux-kernel - RE: [git pull] x86 PAT changes

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: <alpine.LFD.1.10.0804261011030.2813@woody.linux-foundation.org>
Date:	Sat, 26 Apr 2008 10:15:33 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
cc:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: RE: [git pull] x86 PAT changes

On Sat, 26 Apr 2008, Pallipadi, Venkatesh wrote:
> 
> Agreed that NONPROMISC_DEVMEM is not really needed for read/write. But,
> we will still need it for /dev/mem.

If so, just disable it unconditionally for mmap.

As mentioned, that's really just a return to original Linux /dev/mmap 
semantics: long ago (well, not _that_ long ago) we never used to be able 
to mmap() normal kernel memory, because the page counts would get screwed 
up on pages that weren't marked PG_Reserved.

So the traditional Linux behavior for mmap() on /dev/mem was always to 
only allow it on memory that either had no "struct page *" backing at all, 
or that was marked PG_Reserved (ie the ISA hole ay 640k-1M and things like 
the BIOS tables etc).

Going back to that doesn't sound horrible.

		Linus
--
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/