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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E844C433EF for ; Mon, 11 Jul 2022 09:38:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233048AbiGKJiQ (ORCPT ); Mon, 11 Jul 2022 05:38:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53062 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233037AbiGKJh2 (ORCPT ); Mon, 11 Jul 2022 05:37:28 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE36583F01; Mon, 11 Jul 2022 02:19:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 4E822B80E74; Mon, 11 Jul 2022 09:19:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFEE7C34115; Mon, 11 Jul 2022 09:19:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657531172; bh=iQ84uY8s4fGiSftDNeEMZ8xdGgAqkR5pl9zjUgtGbxg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HUqu6EdBDLjbTxIWGJgfJPCpfGMvgHhP58nTeruP9JfrMiUo8EB8xjATKOgCxQlur AbdKFQ6kTJnPlW5dhQxd68y0VBKWpp1LkoSCDxVYasf+pe+vIQj4s/5QoMwngveA/T e2qz0O3xbC9N3b1WYbwI2xoWR+l0dfPkIvfBHAyU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Liu Shixin , "Matthew Wilcox (Oracle)" Subject: [PATCH 5.15 002/230] mm/filemap: fix UAF in find_lock_entries Date: Mon, 11 Jul 2022 11:04:18 +0200 Message-Id: <20220711090604.132579878@linuxfoundation.org> X-Mailer: git-send-email 2.37.0 In-Reply-To: <20220711090604.055883544@linuxfoundation.org> References: <20220711090604.055883544@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Liu Shixin Release refcount after xas_set to fix UAF which may cause panic like this: page:ffffea000491fa40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x1247e9 head:ffffea000491fa00 order:3 compound_mapcount:0 compound_pincount:0 memcg:ffff888104f91091 flags: 0x2fffff80010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff) ... page dumped because: VM_BUG_ON_PAGE(PageTail(page)) ------------[ cut here ]------------ kernel BUG at include/linux/page-flags.h:632! invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN CPU: 1 PID: 7642 Comm: sh Not tainted 5.15.51-dirty #26 ... Call Trace: __invalidate_mapping_pages+0xe7/0x540 drop_pagecache_sb+0x159/0x320 iterate_supers+0x120/0x240 drop_caches_sysctl_handler+0xaa/0xe0 proc_sys_call_handler+0x2b4/0x480 new_sync_write+0x3d6/0x5c0 vfs_write+0x446/0x7a0 ksys_write+0x105/0x210 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f52b5733130 ... This problem has been fixed on mainline by patch 6b24ca4a1a8d ("mm: Use multi-index entries in the page cache") since it deletes the related code. Fixes: 5c211ba29deb ("mm: add and use find_lock_entries") Signed-off-by: Liu Shixin Acked-by: Matthew Wilcox (Oracle) Signed-off-by: Greg Kroah-Hartman --- mm/filemap.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2090,7 +2090,11 @@ unsigned find_lock_entries(struct addres rcu_read_lock(); while ((page = find_get_entry(&xas, end, XA_PRESENT))) { + unsigned long next_idx = xas.xa_index + 1; + if (!xa_is_value(page)) { + if (PageTransHuge(page)) + next_idx = page->index + thp_nr_pages(page); if (page->index < start) goto put; if (page->index + thp_nr_pages(page) - 1 > end) @@ -2111,13 +2115,11 @@ unlock: put: put_page(page); next: - if (!xa_is_value(page) && PageTransHuge(page)) { - unsigned int nr_pages = thp_nr_pages(page); - + if (next_idx != xas.xa_index + 1) { /* Final THP may cross MAX_LFS_FILESIZE on 32-bit */ - xas_set(&xas, page->index + nr_pages); - if (xas.xa_index < nr_pages) + if (next_idx < xas.xa_index) break; + xas_set(&xas, next_idx); } } rcu_read_unlock();