selinux: ensure the context is NUL terminated in security_context_to_sid_core()
authorPaul Moore <paul@paul-moore.com>
Tue, 28 Nov 2017 23:51:12 +0000 (18:51 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 25 Feb 2018 10:07:48 +0000 (11:07 +0100)
commit116df867dbc12297d0e04cd6540ecad401f4c060
tree319494cea698266d64a445c455ef80696217af95
parentb517942f5126c04fff8ff341cdd6a28b0a8de84f
selinux: ensure the context is NUL terminated in security_context_to_sid_core()

commit ef28df55ac27e1e5cd122e19fa311d886d47a756 upstream.

The syzbot/syzkaller automated tests found a problem in
security_context_to_sid_core() during early boot (before we load the
SELinux policy) where we could potentially feed context strings without
NUL terminators into the strcmp() function.

We already guard against this during normal operation (after the SELinux
policy has been loaded) by making a copy of the context strings and
explicitly adding a NUL terminator to the end.  The patch extends this
protection to the early boot case (no loaded policy) by moving the context
copy earlier in security_context_to_sid_core().

Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Reviewed-By: William Roberts <william.c.roberts@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
security/selinux/ss/services.c