From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: Fam Zheng <fam@euphon.net>,
qemu-devel@nongnu.org,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Cc: "Kevin Wolf" <kwolf@redhat.com>,
qemu-block@nongnu.org, "Markus Armbruster" <armbru@redhat.com>,
"Prasad J Pandit" <ppandit@redhat.com>,
"Bandan Das" <bsd@redhat.com>, "Max Reitz" <mreitz@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: [PATCH v3] docs/secure-coding-practices: Describe how to use 'null-co' block driver
Date: Tue, 1 Jun 2021 07:35:03 +0200 [thread overview]
Message-ID: <20210601053503.1828319-1-philmd@redhat.com> (raw)
Document that security reports must use 'null-co,read-zeroes=on'
because otherwise the memory is left uninitialized (which is an
on-purpose performance feature).
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v3: Simplified using Vladimir suggestion.
---
docs/devel/secure-coding-practices.rst | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/docs/devel/secure-coding-practices.rst b/docs/devel/secure-coding-practices.rst
index cbfc8af67e6..79a3dcd09a3 100644
--- a/docs/devel/secure-coding-practices.rst
+++ b/docs/devel/secure-coding-practices.rst
@@ -104,3 +104,12 @@ structures and only process the local copy. This prevents
time-of-check-to-time-of-use (TOCTOU) race conditions that could cause QEMU to
crash when a vCPU thread modifies guest RAM while device emulation is
processing it.
+
+Use of null-co block drivers
+----------------------------
+
+The ``null-co`` block driver is designed for performance: its read accesses are
+not initialized by default. In case it this driver has to be used for security
+research, it must be used with the ``read-zeroes=on`` option which fills read
+buffers with zeroes. Security issues reported with the default
+(``read-zeroes=off``) will be discarded.
--
2.26.3
next reply other threads:[~2021-06-01 5:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-01 5:35 Philippe Mathieu-Daudé [this message]
2021-06-01 7:16 ` [PATCH v3] docs/secure-coding-practices: Describe how to use 'null-co' block driver Vladimir Sementsov-Ogievskiy
2021-06-01 11:12 ` Kevin Wolf
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=20210601053503.1828319-1-philmd@redhat.com \
--to=philmd@redhat.com \
--cc=armbru@redhat.com \
--cc=bsd@redhat.com \
--cc=fam@euphon.net \
--cc=kwolf@redhat.com \
--cc=mreitz@redhat.com \
--cc=ppandit@redhat.com \
--cc=qemu-block@nongnu.org \
--cc=qemu-devel@nongnu.org \
--cc=vsementsov@virtuozzo.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.