The mm_for_maps function in fs/proc/base.c in the Linux kernel 2.6.30.4 and earlier allows local users to read (1) maps and (2) smaps files under proc/ via vectors related to ELF loading, a setuid process, and a race condition.
https://www.redhat.com/archives/fedora-package-announce/2009-August/msg01256.html
https://rhn.redhat.com/errata/RHSA-2009-1540.html
https://exchange.xforce.ibmcloud.com/vulnerabilities/52401
https://bugzilla.redhat.com/show_bug.cgi?id=516171
http://www.vupen.com/english/advisories/2009/2246
http://www.securityfocus.com/bid/36019
http://www.openwall.com/lists/oss-security/2009/08/11/1
http://www.debian.org/security/2010/dsa-2005
http://secunia.com/advisories/36501
http://secunia.com/advisories/36265
http://marc.info/?l=linux-kernel&m=124718949821250
http://marc.info/?l=linux-kernel&m=124718946021193
http://lkml.org/lkml/2009/6/23/653