From: Dave Chinner <david@fromorbit.com>
To: Kees Cook <keescook@chromium.org>
Cc: Jason Yan <yanaijie@huawei.com>,
kernel-hardening@lists.openwall.com,
linux-fsdevel@vger.kernel.org
Subject: Re: CONFIG_HARDENED_USERCOPY
Date: Fri, 30 Aug 2019 14:29:58 +1000 [thread overview]
Message-ID: <20190830042958.GC7777@dread.disaster.area> (raw)
In-Reply-To: <201908290914.F0F929EA@keescook>
On Thu, Aug 29, 2019 at 09:15:36AM -0700, Kees Cook wrote:
> On Thu, Aug 29, 2019 at 08:42:30PM +0800, Jason Yan wrote:
> > We found an issue of kernel bug related to HARDENED_USERCOPY.
> > When copying an IO buffer to userspace, HARDENED_USERCOPY thought it is
> > illegal to copy this buffer. Actually this is because this IO buffer was
> > merged from two bio vectors, and the two bio vectors buffer was allocated
> > with kmalloc() in the filesystem layer.
>
> Ew. I thought the FS layer was always using page_alloc?
No, they don't. It's perfectly legal to use heap memory for bio
buffers - we've been doing it since, at least, XFS got merged all
those years ago.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2019-08-30 4:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 12:42 CONFIG_HARDENED_USERCOPY Jason Yan
2019-08-29 16:15 ` CONFIG_HARDENED_USERCOPY Kees Cook
2019-08-30 4:29 ` Dave Chinner [this message]
2019-08-30 19:47 ` CONFIG_HARDENED_USERCOPY Kees Cook
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