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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 4594CC433E0 for ; Tue, 29 Dec 2020 23:15:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1743421D94 for ; Tue, 29 Dec 2020 23:15:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726284AbgL2XPr (ORCPT ); Tue, 29 Dec 2020 18:15:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:37816 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726281AbgL2XPr (ORCPT ); Tue, 29 Dec 2020 18:15:47 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 26F1E22287; Tue, 29 Dec 2020 23:14:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1609283687; bh=EUBUYzUVxiCfDEWYNoVbTWvr07q5l1xLhwxWpkqkpOY=; h=Date:From:To:Subject:In-Reply-To:From; b=utBJoZy6Ql5YA1GEpxesMxbYOs6i0hXOYwiTuJlWnDD7n10B2fcDmTysdlPnHr4k3 SKbZl0p4frVCxpHFekKNx7AlKt+EnrBy7XmFD3o37/QYZo6FUGZPhqa7Y7BIaAwuLg cdm7a8CxIC3FQCFmHO7e1bDetawaBvrBCy8ZxgOU= Date: Tue, 29 Dec 2020 15:14:46 -0800 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@google.com, aryabinin@virtuozzo.com, dvyukov@google.com, glider@google.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, walter-zh.wu@mediatek.com Subject: [patch 09/16] kasan: fix null pointer dereference in kasan_record_aux_stack Message-ID: <20201229231446.l1zpffxO9%akpm@linux-foundation.org> In-Reply-To: <20201229151349.3285926ec0d1f65a27ac8534@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Walter Wu Subject: kasan: fix null pointer dereference in kasan_record_aux_stack Syzbot reported the following [1]: BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 2d993067 P4D 2d993067 PUD 19a3c067 PMD 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 3852 Comm: kworker/1:2 Not tainted 5.10.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events free_ipc RIP: 0010:kasan_record_aux_stack+0x77/0xb0 Add null checking slab object from kasan_get_alloc_meta() in order to avoid null pointer dereference. [1] https://syzkaller.appspot.com/x/log.txt?x=10a82a50d00000 Link: https://lkml.kernel.org/r/20201228080018.23041-1-walter-zh.wu@mediatek.com Signed-off-by: Walter Wu Suggested-by: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Andrey Konovalov Cc: Alexander Potapenko Signed-off-by: Andrew Morton --- mm/kasan/generic.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/kasan/generic.c~kasan-fix-null-pointer-dereference-in-kasan_record_aux_stack +++ a/mm/kasan/generic.c @@ -337,6 +337,8 @@ void kasan_record_aux_stack(void *addr) cache = page->slab_cache; object = nearest_obj(cache, page, addr); alloc_meta = kasan_get_alloc_meta(cache, object); + if (!alloc_meta) + return; alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0]; alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT); _