From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28675C169C4 for ; Sun, 3 Feb 2019 14:24:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ECD6B2084A for ; Sun, 3 Feb 2019 14:24:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727815AbfBCOYn (ORCPT ); Sun, 3 Feb 2019 09:24:43 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55792 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730468AbfBCOVW (ORCPT ); Sun, 3 Feb 2019 09:21:22 -0500 Received: from cable-78.29.236.164.coditel.net ([78.29.236.164] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gqIe9-0006Qa-E3; Sun, 03 Feb 2019 14:21:21 +0000 Received: from ben by deadeye with local (Exim 4.92-RC4) (envelope-from ) id 1gqI9s-0007PU-CS; Sun, 03 Feb 2019 14:50:04 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Jens Axboe" , "Dan Carpenter" , "Jeff Moyer" , "Matthew Wilcox" Date: Sun, 03 Feb 2019 14:45:08 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 277/305] aio: fix spectre gadget in lookup_ioctx In-Reply-To: X-SA-Exim-Connect-IP: 78.29.236.164 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jeff Moyer commit a538e3ff9dabcdf6c3f477a373c629213d1c3066 upstream. Matthew pointed out that the ioctx_table is susceptible to spectre v1, because the index can be controlled by an attacker. The below patch should mitigate the attack for all of the aio system calls. Reported-by: Matthew Wilcox Reported-by: Dan Carpenter Signed-off-by: Jeff Moyer Signed-off-by: Jens Axboe [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- fs/aio.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/aio.c +++ b/fs/aio.c @@ -43,6 +43,7 @@ #include #include +#include #include "internal.h" @@ -1022,6 +1023,7 @@ static struct kioctx *lookup_ioctx(unsig if (!table || id >= table->nr) goto out; + id = array_index_nospec(id, table->nr); ctx = rcu_dereference(table->table[id]); if (ctx && ctx->user_id == ctx_id) { if (percpu_ref_tryget_live(&ctx->users))