Bug 1513523 (CVE-2017-8807) - CVE-2017-8807 varnish: Data leak - ‘-sfile’ Stevedore transient objects
Summary: CVE-2017-8807 varnish: Data leak - ‘-sfile’ Stevedore transient objects
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2017-8807
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1513524
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-11-15 15:09 UTC by Adam Mariš
Modified: 2021-02-17 01:14 UTC (History)
4 users (show)

Fixed In Version: varnish 4.1.9, varnish 5.2.1
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Clone Of:
Environment:
Last Closed: 2018-05-03 10:48:12 UTC


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Description Adam Mariš 2017-11-15 15:09:12 UTC
A wrong if statement in the varnishd source code means that synthetic objects in stevedores which over-allocate, may leak up to page size of data from a malloc(3) memory allocation.

In a unpredictable percentage of the cases where this condition arises, a segmentation fault will happen instead.

All the following conditions are required to trigger the problem:

    A -sfile or -spersistent stevedore must be configured
    A synthetic object must be created in vcl_backend_error{}
    The synthetic object ends up in the file or persistent stevedore.

For the third condition can arise in two different ways:

    The stevedore named Transient is configured as -sfile or -spersistent (The default is -smalloc)
    The default stevedore is -sfile or -spersistent and the synthetic object is given a TTL larger than the shortlived parameter (default: 10 seconds.)

Affected versions: 4.1.0 to 5.2.0

Upstream patch:

https://github.com/varnishcache/varnish-cache/commit/176f8a075a

External References:

https://varnish-cache.org/security/VSV00002.html

Comment 1 Adam Mariš 2017-11-15 15:09:24 UTC
Acknowledgments:

Name: the Varnish project

Comment 2 Adam Mariš 2017-11-15 15:09:43 UTC
Created varnish tracking bugs for this issue:

Affects: fedora-all [bug 1513524]


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