From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>
Cc: Juergen Gross <jgross@suse.com>,
xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
Stefano Stabellini <sstabellini@kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH] xen/events: avoid NULL pointer dereference in evtchn_from_irq()
Date: Thu, 21 May 2020 17:57:26 -0400 [thread overview]
Message-ID: <c36de3eb-c0ad-45e1-e08b-cb7d86d197f6@oracle.com> (raw)
In-Reply-To: <20200521184602.GP98582@mail-itl>
On 5/21/20 2:46 PM, Marek Marczykowski-Górecki wrote:
> On Thu, May 21, 2020 at 01:22:03PM -0400, Boris Ostrovsky wrote:
>> On 3/19/20 3:14 AM, Juergen Gross wrote:
>>> There have been reports of races in evtchn_from_irq() where the info
>>> pointer has been NULL.
>>>
>>> Avoid that case by testing info before dereferencing it.
>>>
>>> In order to avoid accessing a just freed info structure do the kfree()
>>> via kfree_rcu().
>>
>> Looks like noone ever responded to this.
>>
>>
>> This change looks fine but is there a background on the problem? I
>> looked in the archives and didn't find the relevant discussion.
> Here is the original bug report:
> https://xen.markmail.org/thread/44apwkwzeme4uavo
>
Thanks. Do we know what the race is? Is it because an event is being
delivered from a dying guest who is in the process of tearing down event
channels?
-boris
next prev parent reply other threads:[~2020-05-21 21:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 7:14 [PATCH] xen/events: avoid NULL pointer dereference in evtchn_from_irq() Juergen Gross
2020-03-19 16:01 ` Boris Ostrovsky
2020-05-21 17:22 ` Boris Ostrovsky
2020-05-21 18:46 ` Marek Marczykowski-Górecki
2020-05-21 21:57 ` Boris Ostrovsky [this message]
2020-05-22 8:18 ` Jürgen Groß
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=c36de3eb-c0ad-45e1-e08b-cb7d86d197f6@oracle.com \
--to=boris.ostrovsky@oracle.com \
--cc=jgross@suse.com \
--cc=linux-kernel@vger.kernel.org \
--cc=marmarek@invisiblethingslab.com \
--cc=sstabellini@kernel.org \
--cc=stable@vger.kernel.org \
--cc=xen-devel@lists.xenproject.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).