From: Linus Torvalds <torvalds@linux-foundation.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>,
"security@kernel.org" <security@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Nick Piggin <npiggin@kernel.dk>
Subject: Re: [RFC PATCH (resend)] block layer zero-copy: missing access_ok() check
Date: Fri, 15 Mar 2013 11:01:16 -0700 [thread overview]
Message-ID: <CA+55aFwuL-nB=xDfCfP1+Sn2Q0DEruhWcsrp_oP2meEyeF71jg@mail.gmail.com> (raw)
In-Reply-To: <20130315175710.GA2748@Krystal>
On Fri, Mar 15, 2013 at 10:57 AM, Mathieu Desnoyers
<mathieu.desnoyers@efficios.com> wrote:
>
> In addition to get_user_pages_fast() issues, I see that there are many
> direct callers of get_user_pages() that seem to assume that access
> checks are performed within this function.
get_user_pages() does check permissions. It looks up the vma and
checks them there, which is much more than access_ok() ever does.
> AFAIU, on architectures that
> have a _PAGE_USER flag, this check is performed internally by pgd_bad()
> and pud_bad(), but what happens to all the others ?
Irrelevant. See above.
Linus
next prev parent reply other threads:[~2013-03-15 18:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20130315133748.GA31887@Krystal>
[not found] ` <20130315152326.GM31875@kernel.dk>
[not found] ` <20130315155808.GB1659@Krystal>
[not found] ` <CA+55aFxW0vkpgJCpJVJVqDmDG61P_AOoVMFVhfqVxM45Mj-LNA@mail.gmail.com>
[not found] ` <20130315171000.GA2342@Krystal>
2013-03-15 17:21 ` [RFC PATCH (resend)] block layer zero-copy: missing access_ok() check Linus Torvalds
2013-03-15 17:57 ` Mathieu Desnoyers
2013-03-15 18:01 ` Linus Torvalds [this message]
2013-03-15 18:04 ` Linus Torvalds
2013-03-15 18:07 ` Mathieu Desnoyers
2013-03-18 6:51 ` Benjamin Herrenschmidt
2013-03-21 21:33 ` David Miller
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