Red Hat Bugzilla – Bug 499549
kernel: proc: avoid information leaks to non-privileged processes [rhel-4.8.z]
Last modified: 2009-06-30 04:06:52 EDT
+++ This bug was initially created as a clone of Bug #499541 +++
Description of problem:
By using the same test as is used for /proc/pid/maps and /proc/pid/smaps, only allow processes that can ptrace() a given process to see information that might be used to bypass address space layout randomization (ASLR). These include eip, esp, wchan, and start_stack in /proc/pid/stat as well as the non-symbolic output from /proc/pid/wchan.
ASLR can be bypassed by sampling eip as shown by the proof-of-concept code at http://code.google.com/p/fuzzyaslr/ As part of a presentation (http://www.cr0.org/paper/to-jt-linux-alsr-leak.pdf) esp and wchan were also noted as possibly usable information leaks as well. The start_stack address also leaks potentially useful information.
Upstream commit: http://git.kernel.org/linus/f83ce3e6b02d5e48b3a43b001390e2b58820389d
--- Additional comment from email@example.com on 2009-05-07 02:09:48 EDT ---
Created an attachment (id=342773)
Committed in 89.0.3
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.