It was found that Subversion's mod_dav_svn Apache HTTPD server module will crash when a LOCK request is made against activity URLs. This can lead to a DoS.
An activity URL is used by the server to map transactions in the repository to an incoming commit by a client. They are created by using the MKACTIVITY http method on the activity URL the client wishes to create. Activity URLs following the pattern of having /!svn/act/$uuid where $uuid is some unique id the client chooses to use.
The denial of service described here issues a LOCK request on an activity URL. There is no meaning to this request in the DAV based HTTP protocols that Subversion uses. There is a flaw in mod_dav_svn that improperly tries to process this request instead of rejecting it and results in an attempt to access invalid memory (NULL). The invalid memory access causes the httpd child process to segfault.
Red Hat would like to thank the Apache Subversion project for reporting this issue. Upstream acknowledges Ben Reser as the original reporter of this flaw.
Created attachment 717969 [details]
Created attachment 717970 [details]
This issue affects the version of subversion as shipped with Red Hat Enterprise Linux 5 and 6.
This issue affects the version of subversion as shipped with Fedora 17 and Fedora 18.
Created subversion tracking bugs for this issue
Affects: fedora-all [bug 948813]
This issue has been addressed in following products:
Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 5
Via RHSA-2013:0737 https://rhn.redhat.com/errata/RHSA-2013-0737.html