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From: Catalin Marinas <catalin.marinas@arm.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Mark Rutland <mark.rutland@arm.com>,
Kate Stewart <kstewart@linuxfoundation.org>,
linux-doc@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
Linux Memory Management List <linux-mm@kvack.org>,
Ingo Molnar <mingo@kernel.org>,
Jacob Bramley <Jacob.Bramley@arm.com>,
Jonathan Corbet <corbet@lwn.net>,
Dmitry Vyukov <dvyukov@google.com>,
Bart Van Assche <bart.vanassche@wdc.com>,
Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
Evgeniy Stepanov <eugenis@google.com>,
Kees Cook <keescook@chromium.org>,
Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
Lee Smith <Lee.Smith@arm.com>,
Dan Williams <dan.j.williams@intel.com>,
Robin Murphy <robin.murphy@arm.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Kostya Serebryany <kcc@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
LKML <linux-kernel@vger.kernel.org>,
James Morse <james.morse@arm.com>,
"Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
Philippe Ombredanne <pombredanne@nexb.com>,
Andrew Morton <akpm@linux-foundation.org>,
Zi Yan <zi.yan@cs.rutgers.edu>
Subject: Re: [PATCH 4/6] mm, arm64: untag user addresses in mm/gup.c
Date: Tue, 8 May 2018 16:11:38 +0100 [thread overview]
Message-ID: <20180508151137.zguepljs3pa7xv5g@armageddon.cambridge.arm.com> (raw)
In-Reply-To: <CAAeHK+yTbmZfkeNbqbo+J90zsjsM99rwnYBGfQBxphHMMfgD7A@mail.gmail.com>
On Wed, May 02, 2018 at 07:25:17PM +0200, Andrey Konovalov wrote:
> On Wed, May 2, 2018 at 5:36 PM, Kirill A. Shutemov
> <kirill.shutemov@linux.intel.com> wrote:
> > On Wed, May 02, 2018 at 02:38:42PM +0000, Andrey Konovalov wrote:
> >> > Does having a tagged address here makes any difference? I couldn't hit a
> >> > failure with my simple tests (LD_PRELOAD a library that randomly adds
> >> > tags to pointers returned by malloc).
> >>
> >> I think you're right, follow_page_mask is only called from
> >> __get_user_pages, which already untagged the address. I'll remove
> >> untagging here.
> >
> > It also called from follow_page(). Have you covered all its callers?
>
> Oh, missed that, will take a look.
>
> Thinking about that, would it make sense to add untagging to find_vma
> (and others) instead of trying to cover all find_vma callers?
I don't think adding the untagging to find_vma() is sufficient. In many
cases the caller does a subsequent check like 'start < vma->vm_start'
(see sys_msync() as an example, there are a few others as well). What I
did in my tests was a WARN_ON_ONCE() in find_vma() if the address is
tagged.
--
Catalin
next prev parent reply other threads:[~2018-05-08 15:11 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-18 18:53 [PATCH 0/6] arm64: untag user pointers passed to the kernel Andrey Konovalov
2018-04-18 18:53 ` [PATCH 1/6] arm64: add type casts to untagged_addr macro Andrey Konovalov
2018-04-18 18:53 ` [PATCH 2/6] uaccess: add untagged_addr definition for other arches Andrey Konovalov
2018-04-18 18:53 ` [PATCH 3/6] arm64: untag user addresses in copy_from_user and others Andrey Konovalov
2018-04-26 15:47 ` Catalin Marinas
2018-05-02 15:29 ` Andrey Konovalov
2018-04-18 18:53 ` [PATCH 4/6] mm, arm64: untag user addresses in mm/gup.c Andrey Konovalov
2018-04-26 17:47 ` Catalin Marinas
2018-05-02 14:38 ` Andrey Konovalov
2018-05-02 15:36 ` Kirill A. Shutemov
2018-05-02 17:25 ` Andrey Konovalov
2018-05-03 14:09 ` Andrey Konovalov
2018-05-03 15:24 ` Kirill A. Shutemov
2018-05-03 16:51 ` Andrey Konovalov
2018-05-08 15:11 ` Catalin Marinas [this message]
2018-05-11 12:36 ` Andrey Konovalov
2018-04-18 18:53 ` [PATCH 5/6] lib, arm64: untag addrs passed to strncpy_from_user and strnlen_user Andrey Konovalov
2018-04-18 18:53 ` [PATCH 6/6] arm64: update Documentation/arm64/tagged-pointers.txt Andrey Konovalov
2018-04-19 9:33 ` [PATCH 0/6] arm64: untag user pointers passed to the kernel Kirill A. Shutemov
2018-04-25 14:45 ` Andrey Konovalov
2018-04-26 17:56 ` Catalin Marinas
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