Added checks to prevent overflow in rle file.

CVE assignment:

http://seclists.org/oss-sec/2016/q2/459

Upstream patch:

https://anonscm.debian.org/cgit/collab-maint/imagemagick.git/commit/?h=debian-patches/6.8.9.9-4-for-upstream&id=2d90693af41a363a988a9db3a91a15f9ca7c7370

An out-of-bounds read flaw was found in the way Expat processed certain input. A remote attacker could send specially crafted XML that, when parsed by an application using the Expat library, would cause that application to crash or, possibly, execute arbitrary code with the permission of the user running the application.

GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed function definitions in the values of environment variables, which allows remote attackers to write to files or possibly have unknown other impact via a crafted environment, as demonstrated by vectors involving the ForceCommand feature in OpenSSH sshd, the modcgi and modcgid modules in the Apache HTTP Server, scripts executed by unspecified DHCP clients, and other situations in which setting the environment occurs across a privilege boundary from Bash execution. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-6271.

A flaw was found in the bash functionality that evaluates specially formatted environment variables passed to it from another environment. An attacker could use this feature to override or bypass restrictions to the environment to execute shell commands before restrictions have been applied. Certain services and applications allow remote unauthenticated attackers to provide environment variables, allowing them to exploit this issue.

Acknowledgements:

Red Hat would like to thank Stephane Chazelas for reporting this issue.