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=-5.1 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_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 5530EC433E0 for ; Tue, 26 May 2020 19:16:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DB872053B for ; Tue, 26 May 2020 19:16:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590520565; bh=H808ll5pOciU4ZgyBdWkuOSBa/nNmFeGOtSNwFG9MiA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rofdsPw2OsmLHFrXH8AyhXc1g2mkEedNzZfo+it7DCeXeMU5yVtAuxgyblwxYd6Dw qO7wRPM2qm7wot6e1n1B2QtGUQ2nzecQBRjCoyUsNXUnv8dq0EYQT/iHgXdOuz68up gejn4zMZiri+dvJchIzTNbEyAGNJLeYXBsHwUrW8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391967AbgEZTQE (ORCPT ); Tue, 26 May 2020 15:16:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:48066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404599AbgEZTP7 (ORCPT ); Tue, 26 May 2020 15:15:59 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 777BF2053B; Tue, 26 May 2020 19:15:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590520559; bh=H808ll5pOciU4ZgyBdWkuOSBa/nNmFeGOtSNwFG9MiA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A6sl0p3RM5uidaK1/cXUy6q6WSBAp7d/So7InFN0Z49cCYFwKHG6tXLc9VvYqzGm8 mSDxG0zXG2aE1c5c8JB8e+lYoc+191inEEpf7alnq06FHTtJkYPxduIuo0Qz4l7gPp 2Av75tyYFlLUbxO47JKq1g2/YKDHnw5szEbkYysg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Uladzislau Rezki , Vitaly Wool , Andrew Morton , Qian Cai , Raymond Jennings , Linus Torvalds Subject: [PATCH 5.6 113/126] z3fold: fix use-after-free when freeing handles Date: Tue, 26 May 2020 20:54:10 +0200 Message-Id: <20200526183947.013870148@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526183937.471379031@linuxfoundation.org> References: <20200526183937.471379031@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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(-) --- a/mm/z3fold.c +++ b/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);