From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756015AbdGSR7g (ORCPT ); Wed, 19 Jul 2017 13:59:36 -0400 Received: from mail-pg0-f43.google.com ([74.125.83.43]:38088 "EHLO mail-pg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755986AbdGSR7U (ORCPT ); Wed, 19 Jul 2017 13:59:20 -0400 From: Thomas Garnier To: Russell King , Thomas Garnier , Thomas Gleixner , Catalin Marinas , Will Deacon , Dave Martin , Chris Metcalf , Pratyush Anand , leonard.crestez@nxp.com Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: [PATCH 3/3] arm64/syscalls: Move address limit check in loop Date: Wed, 19 Jul 2017 10:59:00 -0700 Message-Id: <20170719175900.124074-3-thgarnie@google.com> X-Mailer: git-send-email 2.14.0.rc0.284.gd933b75aa4-goog In-Reply-To: <20170719175900.124074-1-thgarnie@google.com> References: <20170719175900.124074-1-thgarnie@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The original bug was reported on arm but I am fixing arm64 too because it has a similar code pattern. The work pending loop can call set_fs after addr_limit_user_check removed the _TIF_FSCHECK flag. To prevent the infinite loop, move the addr_limit_user_check call at the beginning of the loop. Fixes: cf7de27ab351 ("arm64/syscalls: Check address limit on user-mode return") Reported-by: Leonard Crestez Signed-off-by: Thomas Garnier --- arch/arm64/kernel/signal.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index e3e3293d1123..8e2705983e1d 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -751,10 +751,10 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, */ trace_hardirqs_off(); - /* Check valid user FS if needed */ - addr_limit_user_check(); - do { + /* Check valid user FS if needed */ + addr_limit_user_check(); + if (thread_flags & _TIF_NEED_RESCHED) { schedule(); } else { -- 2.14.0.rc0.284.gd933b75aa4-goog