From: Christoph Hellwig <hch@infradead.org>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: DRI Development <dri-devel@lists.freedesktop.org>,
LKML <linux-kernel@vger.kernel.org>,
kvm@vger.kernel.org, linux-mm@kvack.org,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org,
linux-s390@vger.kernel.org,
Daniel Vetter <daniel.vetter@intel.com>,
Jason Gunthorpe <jgg@ziepe.ca>, Kees Cook <keescook@chromium.org>,
Dan Williams <dan.j.williams@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
John Hubbard <jhubbard@nvidia.com>,
J??r??me Glisse <jglisse@redhat.com>, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH v4 08/15] mm: Add unsafe_follow_pfn
Date: Thu, 29 Oct 2020 08:56:44 +0000 [thread overview]
Message-ID: <20201029085644.GA25658@infradead.org> (raw)
In-Reply-To: <20201026105818.2585306-9-daniel.vetter@ffwll.ch>
> +int unsafe_follow_pfn(struct vm_area_struct *vma, unsigned long address,
> + unsigned long *pfn)
The one tab indent here looks weird, normally tis would be two tabs
or aligned aftetthe opening brace.
> +{
> +#ifdef CONFIG_STRICT_FOLLOW_PFN
> + pr_info("unsafe follow_pfn usage rejected, see CONFIG_STRICT_FOLLOW_PFN\n");
> + return -EINVAL;
> +#else
> + WARN_ONCE(1, "unsafe follow_pfn usage\n");
> + add_taint(TAINT_USER, LOCKDEP_STILL_OK);
> +
> + return follow_pfn(vma, address, pfn);
> +#endif
Woudn't this be a pretty good use case of "if (IS_ENABLED(...)))"?
Also I'd expect the inverse polarity of the config option, that is
a USAFE_FOLLOW_PFN option to enable to unsafe behavior.
> +/**
> + * unsafe_follow_pfn - look up PFN at a user virtual address
> + * @vma: memory mapping
> + * @address: user virtual address
> + * @pfn: location to store found PFN
> + *
> + * Only IO mappings and raw PFN mappings are allowed.
> + *
> + * Returns zero and the pfn at @pfn on success, -ve otherwise.
> + */
> +int unsafe_follow_pfn(struct vm_area_struct *vma, unsigned long address,
> + unsigned long *pfn)
> +{
> + return follow_pfn(vma, address, pfn);
> +}
> +EXPORT_SYMBOL(unsafe_follow_pfn);
Any reason this doesn't use the warn and disable logic?
next prev parent reply other threads:[~2020-10-29 9:00 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 10:58 [PATCH v4 00/15] follow_pfn and other iomap races Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 01/15] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 02/15] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 03/15] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 04/15] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 05/15] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter
2020-10-26 22:15 ` Tomasz Figa
2020-10-27 8:05 ` Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 06/15] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-10-26 22:03 ` Tomasz Figa
2020-10-26 10:58 ` [PATCH v4 07/15] mm: Close race in generic_access_phys Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 08/15] mm: Add unsafe_follow_pfn Daniel Vetter
2020-10-29 8:56 ` Christoph Hellwig [this message]
2020-10-29 9:23 ` Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 09/15] media/videbuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2020-10-26 22:02 ` Tomasz Figa
2020-10-26 10:58 ` [PATCH v4 10/15] vfio/type1: Mark follow_pfn " Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 11/15] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 12/15] /dev/mem: Only set filp->f_mapping Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 13/15] resource: Move devmem revoke code to resource framework Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 14/15] sysfs: Support zapping of binary attr mmaps Daniel Vetter
2020-10-26 10:58 ` [PATCH v4 15/15] PCI: Revoke mappings like devmem Daniel Vetter
2020-10-29 8:57 ` [PATCH v4 00/15] follow_pfn and other iomap races Christoph Hellwig
2020-10-29 9:25 ` Daniel Vetter
2020-10-29 9:28 ` Christoph Hellwig
2020-10-29 9:38 ` Daniel Vetter
2020-10-29 10:01 ` Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201029085644.GA25658@infradead.org \
--to=hch@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=dan.j.williams@intel.com \
--cc=daniel.vetter@ffwll.ch \
--cc=daniel.vetter@intel.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=jack@suse.cz \
--cc=jgg@ziepe.ca \
--cc=jglisse@redhat.com \
--cc=jhubbard@nvidia.com \
--cc=keescook@chromium.org \
--cc=kvm@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-samsung-soc@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).