linux-kernel - Re: Generic page fault (Was: libsigsegv ....)

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:	Sat, 28 Feb 2015 16:41:41 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>
Subject: Re: Generic page fault (Was: libsigsegv ....)

On Sat, Feb 28, 2015 at 3:02 PM, Benjamin Herrenschmidt
<benh@...nel.crashing.org> wrote:
>
> Anyway, here's the current patch:

Ok, I think I like this approach better.

Your FAULT_FLAG_EXEC handling is wrong, though. It shouldn't check
VM_WRITE, it should check VM_EXEC. A bit too much copy-paste ;)

Btw, it's quite possible that we could just do all the PF_PROT
handling at the x86 level, before even calling the generic fault
handler. It's not like we even need the vma or the mm semaphore: if
it's a non-write protection fault, we always SIGSEGV. So why even
bother getting the locks and looking up the page tables etc?

Now, that PF_PROT handling isn't exactly performance-critical, but it
might help to remove the odd x86 special case from the generic code.

                      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/