From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20150515080532.244148580@1wt.eu> Date: Fri, 15 May 2015 10:06:16 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Mathias Krause , Oleg Nesterov , Brad Spengler , PaX Team , Thomas Gleixner , Ben Hutchings , Willy Tarreau Subject: [ 46/48] posix-timers: Fix stack info leak in timer_create() MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 In-Reply-To: <9c2783dfae10ef2d1e9b08bcc1e562c5@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Mathias Krause commit 6891c4509c792209c44ced55a60f13954cb50ef4 upstream. 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 Link: http://lkml.kernel.org/r/1412456799-32339-1-git-send-email-minipli@googlemail.com Signed-off-by: Thomas Gleixner [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings (cherry picked from commit 3cd3a349aa3519b88d29845c0bc36bcbae158e93) Signed-off-by: Willy Tarreau --- kernel/posix-timers.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 5e76d22..f2335e8 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -578,6 +578,7 @@ 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; -- 1.7.12.2.21.g234cd45.dirty