Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751240AbaJDVIq (ORCPT ); Sat, 4 Oct 2014 17:08:46 -0400 Received: from mail-wi0-f176.google.com ([209.85.212.176]:57166 "EHLO mail-wi0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750956AbaJDVIp (ORCPT ); Sat, 4 Oct 2014 17:08:45 -0400 From: Mathias Krause To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, Mathias Krause , Oleg Nesterov , Brad Spengler , PaX Team Subject: [PATCH] posix-timers: fix stack info leak in timer_create() Date: Sat, 4 Oct 2014 23:06:39 +0200 Message-Id: <1412456799-32339-1-git-send-email-minipli@googlemail.com> X-Mailer: git-send-email 1.7.10.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If userland creates a timer without specifying a sigevent info, we'll create one ourself, using a stack local variable. Particularly will we use the timer ID as sival_int. But as sigev_value is a union containing a pointer and an int, that assignment will only partially initialize sigev_value on systems where the size of a pointer is bigger than the size of an int. On such systems we'll copy the uninitialized stack bytes from the timer_create() call to userland when the timer actually fires and we're going to deliver the signal. Initialize sigev_value with 0 to plug the stack info leak. Found in the PaX patch, written by the PaX Team. Fixes: 5a9fa7307285 ("posix-timers: kill ->it_sigev_signo and...") Signed-off-by: Mathias Krause Cc: Oleg Nesterov Cc: Brad Spengler Cc: PaX Team Cc: # v2.6.28+ --- kernel/time/posix-timers.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index 42b463ad90f2..31ea01f42e1f 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -636,6 +636,7 @@ SYSCALL_DEFINE3(timer_create, const clockid_t, which_clock, goto out; } } else { + memset(&event.sigev_value, 0, sizeof(event.sigev_value)); event.sigev_notify = SIGEV_SIGNAL; event.sigev_signo = SIGALRM; event.sigev_value.sival_int = new_timer->it_id; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/