From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 1 Aug 2005 20:45:29 -0700 (PDT) From: Linus Torvalds Subject: Re: [patch 2.6.13-rc4] fix get_user_pages bug In-Reply-To: <42EECC1F.9000902@yahoo.com.au> Message-ID: References: <20050801032258.A465C180EC0@magilla.sf.frob.com> <42EDDB82.1040900@yahoo.com.au> <42EECC1F.9000902@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Robin Holt , Andrew Morton , Roland McGrath , Hugh Dickins , linux-mm@kvack.org, linux-kernel List-ID: On Tue, 2 Aug 2005, Nick Piggin wrote: > > Surely this introduces integrity problems when `force` is not set? "force" changes how we test the vma->vm_flags, that was always the meaning from a security standpoint (and that hasn't changed). The old code had this "lookup_write = write && !force;" thing because there it used "force" to _clear_ the write bit test, and that was what caused the race in the first place - next time around we would accept a non-writable page, even if it hadn't actually gotten COW'ed. So no, the patch doesn't introduce integrity problems by ignoring "force". Quite the reverse - it _removes_ the integrity problems by ignoring it there. That's kind of the whole point. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org