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
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