[Acked] [Lucid][CVE-2013-2141] kernel/signal.c: stop info leak via the tkill and the tgkill syscalls

[Andy Whitcroft]

On Thu, Jun 20, 2013 at 01:52:12PM +0100, Luis Henriques wrote:
> Andy Whitcroft <apw at canonical.com> writes:
> 
> > On Thu, Jun 20, 2013 at 12:31:29PM +0100, Luis Henriques wrote:
> >> From: Emese Revfy <re.emese at gmail.com>
> >> 
> >> BugLink: https://bugs.launchpad.net/bugs/1187732
> >> 
> >> CVE-2013-2141
> >> 
> >> This fixes a kernel memory contents leak via the tkill and tgkill syscalls
> >> for compat processes.
> >> 
> >> This is visible in the siginfo_t->_sifields._rt.si_sigval.sival_ptr field
> >> when handling signals delivered from tkill.
> >> 
> >> The place of the infoleak:
> >> 
> >> int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
> >> {
> >>         ...
> >>         put_user_ex(ptr_to_compat(from->si_ptr), &to->si_ptr);
> >>         ...
> >> }
> >> 
> >> Signed-off-by: Emese Revfy <re.emese at gmail.com>
> >> Reviewed-by: PaX Team <pageexec at freemail.hu>
> >> Signed-off-by: Kees Cook <keescook at chromium.org>
> >> Cc: Al Viro <viro at zeniv.linux.org.uk>
> >> Cc: Oleg Nesterov <oleg at redhat.com>
> >> Cc: "Eric W. Biederman" <ebiederm at xmission.com>
> >> Cc: Serge Hallyn <serge.hallyn at canonical.com>
> >> Cc: <stable at vger.kernel.org>
> >> Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
> >> Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
> >> (cherry picked from commit b9e146d8eb3b9ecae5086d373b50fa0c1f3e7f0f)
> >> 
> >> Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
> >> ---
> >>  kernel/signal.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/kernel/signal.c b/kernel/signal.c
> >> index 1c6675b..fb7e242 100644
> >> --- a/kernel/signal.c
> >> +++ b/kernel/signal.c
> >> @@ -2301,7 +2301,7 @@ do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
> >>  
> >>  static int do_tkill(pid_t tgid, pid_t pid, int sig)
> >>  {
> >> -	struct siginfo info;
> >> +	struct siginfo info = {};
> >>  
> >>  	info.si_signo = sig;
> >>  	info.si_errno = 0;
> >> -- 
> >> 1.8.1.2
> >> 
> >> -- 
> >> kernel-team mailing list
> >> kernel-team at lists.ubuntu.com
> >> https://lists.ubuntu.com/mailman/listinfo/kernel-team
> >
> > Matches upstream and looks to do what is claimed.
> >
> > Acked-by: Andy Whitcroft <apw at canonical.com>
> >
> > That this is only for lucid, does that imply we are getting the rest via
> > stable?
> 
> Yes, the fixes for both CVEs are already queued (or released) in the
> stable trees.  Since these patches are already too late for this SRU
> cycle, I guess we can just wait for the stable updates to bring the
> fixes into the other series.

I am sure that works.

-apw