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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 3ECD4C433E0 for ; Sat, 23 May 2020 05:23:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 20FE620759 for ; Sat, 23 May 2020 05:23:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590211394; bh=2GgUabfP0TjV77fo/j+G1COH8CJdyHQfA5O/s6j40hw=; h=Date:From:To:Subject:In-Reply-To:List-ID:From; b=ktBK2NsMrU3YjlLi+fGgsBSMqxZOF++x3XDzdMWiiX6slajQzaFeo7AfOR7/vBexE IIltcUVCE1XnKb4cy105Y6PMBFVoSm3Nt6PvYk6ySXo9H/M+dVWg/YwMVo1QSfpS9w 54VBVWx9yQTO27zaPTh9qRnAWuLT/OTU0jBV7rSU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387612AbgEWFXN (ORCPT ); Sat, 23 May 2020 01:23:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:55716 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387610AbgEWFXN (ORCPT ); Sat, 23 May 2020 01:23:13 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B8DB620814; Sat, 23 May 2020 05:23:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590211393; bh=2GgUabfP0TjV77fo/j+G1COH8CJdyHQfA5O/s6j40hw=; h=Date:From:To:Subject:In-Reply-To:From; b=ehhDgjkf/utTOZ0V9ynmjcSsbgo0wPxm0ILqJpOwhtnuT7H2LdKVOYv8CgkqzzWRB 8HCdHb4DDLqshDvYxE2Hgqa/QfT1/PEC4qSIBBQFnpIFO5hxtkq+aPyzH3cfj6vRaW WpPcgG/MBWPFzK2PZzdpDfYpu/lTS+yA9eJVxv6o= Date: Fri, 22 May 2020 22:23:12 -0700 From: Andrew Morton To: akpm@linux-foundation.org, cai@lca.pw, linux-mm@kvack.org, mm-commits@vger.kernel.org, shentino@gmail.com, stable@vger.kernel.org, torvalds@linux-foundation.org, uladzislau.rezki@sony.com, vitaly.wool@konsulko.com Subject: [patch 10/11] z3fold: fix use-after-free when freeing handles Message-ID: <20200523052312.8XR1NwGDV%akpm@linux-foundation.org> In-Reply-To: <20200522222217.ee14ad7eda7aab1e6697da6c@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Uladzislau Rezki Subject: z3fold: fix use-after-free when freeing handles free_handle() for a foreign handle may race with inter-page compaction, what can lead to memory corruption. To avoid that, take write lock not read lock in free_handle to be synchronized with __release_z3fold_page(). For example KASAN can detect it: [ 33.723357] ================================================================== [ 33.723401] BUG: KASAN: use-after-free in LZ4_decompress_safe+0x2c4/0x3b8 [ 33.723418] Read of size 1 at addr ffffffc976695ca3 by task GoogleApiHandle/4121 [ 33.723428] [ 33.723449] CPU: 0 PID: 4121 Comm: GoogleApiHandle Tainted: P S OE 4.19.81-perf+ #162 [ 33.723461] Hardware name: Sony Mobile Communications. PDX-203(KONA) (DT) [ 33.723473] Call trace: [ 33.723495] dump_backtrace+0x0/0x288 [ 33.723512] show_stack+0x14/0x20 [ 33.723533] dump_stack+0xe4/0x124 [ 33.723551] print_address_description+0x80/0x2e0 [ 33.723566] kasan_report+0x268/0x2d0 [ 33.723584] __asan_load1+0x4c/0x58 [ 33.723601] LZ4_decompress_safe+0x2c4/0x3b8 [ 33.723619] lz4_decompress_crypto+0x3c/0x70 [ 33.723636] crypto_decompress+0x58/0x70 [ 33.723656] zcomp_decompress+0xd4/0x120 ... Apart from that, initialize zhdr->mapped_count in init_z3fold_page() and remove "newpage" variable because it is not used anywhere. Link: http://lkml.kernel.org/r/20200520082100.28876-1-vitaly.wool@konsulko.com Signed-off-by: Uladzislau Rezki Signed-off-by: Vitaly Wool Cc: Qian Cai Cc: Raymond Jennings Cc: Signed-off-by: Andrew Morton --- mm/z3fold.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- a/mm/z3fold.c~z3fold-fix-use-after-free-when-freeing-handles +++ a/mm/z3fold.c @@ -318,16 +318,16 @@ static inline void free_handle(unsigned slots = handle_to_slots(handle); write_lock(&slots->lock); *(unsigned long *)handle = 0; - write_unlock(&slots->lock); - if (zhdr->slots == slots) + if (zhdr->slots == slots) { + write_unlock(&slots->lock); return; /* simple case, nothing else to do */ + } /* we are freeing a foreign handle if we are here */ zhdr->foreign_handles--; is_free = true; - read_lock(&slots->lock); if (!test_bit(HANDLES_ORPHANED, &slots->pool)) { - read_unlock(&slots->lock); + write_unlock(&slots->lock); return; } for (i = 0; i <= BUDDY_MASK; i++) { @@ -336,7 +336,7 @@ static inline void free_handle(unsigned break; } } - read_unlock(&slots->lock); + write_unlock(&slots->lock); if (is_free) { struct z3fold_pool *pool = slots_to_pool(slots); @@ -422,6 +422,7 @@ static struct z3fold_header *init_z3fold zhdr->start_middle = 0; zhdr->cpu = -1; zhdr->foreign_handles = 0; + zhdr->mapped_count = 0; zhdr->slots = slots; zhdr->pool = pool; INIT_LIST_HEAD(&zhdr->buddy); _