Dropbear 2012.55 security release

[Matt Johnston]

Hi all,

Dropbear 2012.55 is now released, available as usual at
https://matt.ucc.asn.au/dropbear/dropbear.html

This fixes a security bug that could potentially allow
arbitrary code execution as root to a user authenticating
using an authorized_keys file with a command="..."
restriction.

Cheers,
Matt

2012.55 - Wednesday 22 February 2012

- Security: Fix use-after-free bug that could be triggered if command="..."
  authorized_keys restrictions are used.  Could allow arbitrary code execution
  or bypass of the command="..." restriction to an authenticated user.
  This bug affects releases 0.52 onwards. Ref CVE-2012-0920.
  Thanks to Danny Fullerton of Mantor Organization for reporting
  the bug.

- Compile fix, only apply IPV6 socket options if they are available in headers
  Thanks to Gustavo Zacarias for the patch

- Overwrite session key memory on exit

- Fix minor memory leak in unusual PAM authentication configurations.
  Thanks to Stathis Voukelatos

- Other small code cleanups