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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLACK,USER_AGENT_GIT 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 A0D12C433E0 for ; Mon, 8 Jun 2020 23:19:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82CCE20814 for ; Mon, 8 Jun 2020 23:19:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591658396; bh=DeTCi+evNa25ktxq1NUlS81kxYThJ6DbPYwt78qnKrc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=sKBI8jynrSpGyi3lwTJHJ6CckQ3ANz2ar57cBnYGLKi4fkvfS1vzrSYLgtiaTB5pK irI1RPJ6prGMyDT7hk7aCvh6STH5yKibI011UYFDW7sFWYAfxSg8MgW5hb8reGG+XM SpzGflPMM6FTlAGRp66+iJlhJB6CNzEGgbWMVz24= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730134AbgFHXTy (ORCPT ); Mon, 8 Jun 2020 19:19:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:37292 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730163AbgFHXQE (ORCPT ); Mon, 8 Jun 2020 19:16:04 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 914762076C; Mon, 8 Jun 2020 23:16:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591658163; bh=DeTCi+evNa25ktxq1NUlS81kxYThJ6DbPYwt78qnKrc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pnSKcxu0oHzosChxZachnqvWDKSeL3Oufd18X6/oMM034JwiLhHy+JJn4+eto5GbP Xeowak7D8p12Q6qA5YLfE7u2Pc28VgNU35yjPSMQIqrESnYIqsi2Y4Bd1yA9OvYp0u uOjk2lpmVwhriM3zADYIwi5almyPw18o1hSqHejs= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Uladzislau Rezki , Vitaly Wool , Andrew Morton , Qian Cai , Raymond Jennings , Linus Torvalds , Greg Kroah-Hartman , linux-mm@kvack.org Subject: [PATCH AUTOSEL 5.6 192/606] z3fold: fix use-after-free when freeing handles Date: Mon, 8 Jun 2020 19:05:17 -0400 Message-Id: <20200608231211.3363633-192-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200608231211.3363633-1-sashal@kernel.org> References: <20200608231211.3363633-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Uladzislau Rezki commit d8f117abb380ba968b5e3ef2042d901c02872a4c upstream. 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: ================================================================== BUG: KASAN: use-after-free in LZ4_decompress_safe+0x2c4/0x3b8 Read of size 1 at addr ffffffc976695ca3 by task GoogleApiHandle/4121 CPU: 0 PID: 4121 Comm: GoogleApiHandle Tainted: P S OE 4.19.81-perf+ #162 Hardware name: Sony Mobile Communications. PDX-203(KONA) (DT) Call trace: LZ4_decompress_safe+0x2c4/0x3b8 lz4_decompress_crypto+0x3c/0x70 crypto_decompress+0x58/0x70 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. Signed-off-by: Uladzislau Rezki Signed-off-by: Vitaly Wool Signed-off-by: Andrew Morton Cc: Qian Cai Cc: Raymond Jennings Cc: Link: http://lkml.kernel.org/r/20200520082100.28876-1-vitaly.wool@konsulko.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/z3fold.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/mm/z3fold.c b/mm/z3fold.c index 42f31c4b53ad..8c3bb5e508b8 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -318,16 +318,16 @@ static inline void free_handle(unsigned long handle) 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 long handle) 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_page(struct page *page, bool headless, 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); -- 2.25.1