LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: ebiederm@xmission.com (Eric W. Biederman)
To: michael@ellerman.id.au
Cc: linux-pci@atrey.karlin.mff.cuni.cz,
	Greg Kroah-Hartman <greg@kroah.com>,
	"David S. Miller" <davem@davemloft.net>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
	daniel.e.wolstenholme@intel.com
Subject: Re: [PATCH 17/21] MSI: Clear the irq_desc's msi pointer on free
Date: Thu, 22 Mar 2007 21:00:47 -0600	[thread overview]
Message-ID: <m1y7lo64v4.fsf@ebiederm.dsl.xmission.com> (raw)
In-Reply-To: <1174604508.5401.7.camel@concordia.ozlabs.ibm.com> (Michael Ellerman's message of "Fri, 23 Mar 2007 10:01:48 +1100")

Michael Ellerman <michael@ellerman.id.au> writes:

> On Thu, 2007-03-22 at 08:23 -0600, Eric W. Biederman wrote:
>> Michael Ellerman <michael@ellerman.id.au> writes:
>> 
>> > Currently we never clear the msi_desc pointer in the irq_desc. This
>> > leaves us with a pointer to free'ed memory hanging around. No one seems
>> > to have hit this, so presumably other parts of the code are protecting
>> > us from ever using the stale pointer .. or we're just lucky, we should
>> > still clear it.
>> 
>> Hmm.  Maybe.  Currently this is done in dynamic_irq_cleanup,
>> at least for everything except sparc64.
>
> OK, I missed that. I still think we should do it here, otherwise there's
> a window, however small, where the msi_desc pointer is pointing at freed
> memory.

After following the code through the current cleanup happens before you are
proposing, and in fact the irq is return to the set of irq's that can
be allocated before you are calling set_irq_msi(irq, NULL).

Therefore you are doing this too late and we need to ensure the
architecture code does this in arch_teardown_msi_irq.

Eric

  reply	other threads:[~2007-03-23  3:10 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20070322105344.A34C6DDF74@ozlabs.org>
2007-03-22 14:23 ` Eric W. Biederman
2007-03-22 23:01   ` Michael Ellerman
2007-03-23  3:00     ` Eric W. Biederman [this message]
2007-03-26  2:57       ` Michael Ellerman
2007-03-26  3:07         ` Eric W. Biederman

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=m1y7lo64v4.fsf@ebiederm.dsl.xmission.com \
    --to=ebiederm@xmission.com \
    --cc=akpm@osdl.org \
    --cc=benh@kernel.crashing.org \
    --cc=daniel.e.wolstenholme@intel.com \
    --cc=davem@davemloft.net \
    --cc=greg@kroah.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@atrey.karlin.mff.cuni.cz \
    --cc=michael@ellerman.id.au \
    --subject='Re: [PATCH 17/21] MSI: Clear the irq_desc'\''s msi pointer on free' \
    /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

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).