The tpm_open function in drivers/char/tpm/tpm.c in the Linux kernel before 2.6.39 does not initialize a certain buffer, which allows local users to obtain potentially sensitive information from kernel memory via unspecified vectors.
https://bugzilla.redhat.com/show_bug.cgi?id=684671
http://www.openwall.com/lists/oss-security/2011/03/15/13
http://ftp.osuosl.org/pub/linux/kernel/v2.6/ChangeLog-2.6.39