linux-kernel - Re: [PATCH v7 05/19] iov_iter: Introduce fault_in_iov_iter

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: <CA+8MBbLLze0siip=h-2hR3XiceBFQCN7uh5BPvqYRyBXgT318g@mail.gmail.com>
Date:   Sat, 28 Aug 2021 15:20:58 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        "Darrick J. Wong" <djwong@...nel.org>, Jan Kara <jack@...e.cz>,
        Matthew Wilcox <willy@...radead.org>,
        cluster-devel <cluster-devel@...hat.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ocfs2-devel@....oracle.com, Borislav Petkov <bp@...en8.de>,
        X86-ML <x86@...nel.org>
Subject: Re: [PATCH v7 05/19] iov_iter: Introduce fault_in_iov_iter_writeable

On Sat, Aug 28, 2021 at 3:12 PM Al Viro <viro@...iv.linux.org.uk> wrote:
> BTW, is #MC triggered on stored to a poisoned cacheline?  Existence of CLZERO
> would seem to argue against that...

No #MC on stores. Just on loads. Note that you can't clear poison
state with a series of small writes to the cache line. But a single
64-byte store might do it (architects didn't want to guarantee that
it would work when I asked about avx512 stores to clear poison
many years ago).

-Tony