UBUNTU: Start new release

Ignore: yes
Signed-off-by: Brad Figg <brad.figg@canonical.com>
exec: use -ELOOP for max recursion depth

CVE-2012-4530

BugLink: http://bugs.launchpad.net/bugs/1068888

To avoid an explosion of request_module calls on a chain of abusive
scripts, fail maximum recursion with -ELOOP instead of -ENOEXEC. As soon
as maximum recursion depth is hit, the error will fail all the way back
up the chain, aborting immediately.

This also has the side-effect of stopping the user's shell from attempting
to reexecute the top-level file as a shell script. As seen in the
dash source:

        if (cmd != path_bshell && errno == ENOEXEC) {
                *argv-- = cmd;
                *argv = cmd = path_bshell;
                goto repeat;
        }

The above logic was designed for running scripts automatically that lacked
the "#!" header, not to re-try failed recursion. On a legitimate -ENOEXEC,
things continue to behave as the shell expects.

Additionally, when tracking recursion, the binfmt handlers should not be
involved. The recursion being tracked is the depth of calls through
search_binary_handler(), so that function should be exclusively responsible
for tracking the depth.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: halfdog <me@halfdog.net>
Cc: P J P <ppandit@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

(backported from commit d740269867021faf4ce38a449353d2b986c34a67)
Conflicts:
	fs/binfmt_misc.c
	fs/exec.c
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Acked-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Acked-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
UBUNTU: SAUCE: exec: do not leave bprm->interp on stack

CVE-2012-4530

BugLink: http://bugs.launchpad.net/bugs/1068888

If a series of scripts are executed, each triggering module loading via
unprintable bytes in the script header, kernel stack contents can leak
into the command line.

Normally execution of binfmt_script and binfmt_misc happens recursively.
However, when modules are enabled, and unprintable bytes exist in the
bprm->buf, execution will restart after attempting to load matching binfmt
modules.  Unfortunately, the logic in binfmt_script and binfmt_misc does
not expect to get restarted.  They leave bprm->interp pointing to their
local stack.  This means on restart bprm->interp is left pointing into
unused stack memory which can then be copied into the userspace argv
areas.

After additional study, it seems that both recursion and restart remains
the desirable way to handle exec with scripts, misc, and modules.  As
such, we need to protect the changes to interp.

This changes the logic to require allocation for any changes to the
bprm->interp.  To avoid adding a new kmalloc to every exec, the default
value is left as-is.  Only when passing through binfmt_script or
binfmt_misc does an allocation take place.

For a proof of concept, see DoTest.sh from:
http://www.halfdog.net/Security/2012/LinuxKernelBinfmtScriptStackDataDisclosure/

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: halfdog <me@halfdog.net>
Cc: P J P <ppandit@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Acked-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Acked-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
UBUNTU: Ubuntu-2.6.32-45.102

Signed-off-by: Brad Figg <brad.figg@canonical.com>