From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756005AbcEWNnZ (ORCPT ); Mon, 23 May 2016 09:43:25 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:33229 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752100AbcEWNnX (ORCPT ); Mon, 23 May 2016 09:43:23 -0400 Date: Mon, 23 May 2016 15:43:20 +0200 From: Michal Hocko To: Oleg Nesterov Cc: Aleksa Sarai , LKML , Martin Schwidefsky , Heiko Carstens , linux-s390@vger.kernel.org, Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , x86@kernel.org Subject: [PATCH] s390: fix info leak in do_sigsegv Message-ID: <20160523134318.GT2278@dhcp22.suse.cz> References: <20160523111630.GN2278@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160523111630.GN2278@dhcp22.suse.cz> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org OK, Martin would prefer a simple patch so here we go. --- >>From de1ad037f3181e795ef0e66a61b8fbe1157f66cc Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Mon, 23 May 2016 15:35:51 +0200 Subject: [PATCH] s390: fix info leak in do_sigsegv Aleksa has reported incorrect si_errno value when stracing task which received SIGSEGV: [pid 20799] --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_errno=2510266, si_addr=0x100000000000000} The reason seems to be that do_sigsegv is not initializing siginfo structure defined on the stack completely so it will leak 4B of the previous stack content. Fix it simply by initializing si_errno to 0 (same as do_sigbus does already). Cc: stable # introduced pre-git times Reported-by: Aleksa Sarai Signed-off-by: Michal Hocko --- arch/s390/mm/fault.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index 7a3144017301..19288c1b36d3 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -250,6 +250,7 @@ static noinline void do_sigsegv(struct pt_regs *regs, int si_code) report_user_fault(regs, SIGSEGV, 1); si.si_signo = SIGSEGV; + si.si_errno = 0; si.si_code = si_code; si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK); force_sig_info(SIGSEGV, &si, current); -- 2.8.1 -- Michal Hocko SUSE Labs