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 A5AB2C433EF for ; Fri, 27 May 2022 16:37:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349330AbiE0QhK (ORCPT ); Fri, 27 May 2022 12:37:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354101AbiE0QfG (ORCPT ); Fri, 27 May 2022 12:35:06 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E15D13B2AE for ; Fri, 27 May 2022 09:35:04 -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 sin.source.kernel.org (Postfix) with ESMTPS id 51B30CE251B for ; Fri, 27 May 2022 16:35:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA86AC385B8; Fri, 27 May 2022 16:35:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1653669301; bh=oBTnSSysZluk97OiWD3A1C6Scmu/Gh4FfRtTQ/W37KA=; h=Date:To:From:Subject:From; b=mFDFoCHqsE4GSF0cKSP0KXPj1WztnbA3paJoqD0c+p3JedKM8xEMf5BOwyi+Fl2Nb Drqv8hqZaadIV0tbeeu+OADyufBUkrO+rrws/W75VRVBDsotBa87Q5RKHDXJUApoPp 0YxYXPDiPUGO25bNqFzkAq4LlZHOsGqZZYhhNHxY= Date: Fri, 27 May 2022 09:35:01 -0700 To: mm-commits@vger.kernel.org, vitaly.wool@konsulko.com, linmiaohe@huawei.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-z3fold-fix-z3fold_page_migrate-races-with-z3fold_map.patch removed from -mm tree Message-Id: <20220527163501.AA86AC385B8@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The quilt patch titled Subject: mm/z3fold: fix z3fold_page_migrate races with z3fold_map has been removed from the -mm tree. Its filename was mm-z3fold-fix-z3fold_page_migrate-races-with-z3fold_map.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Miaohe Lin Subject: mm/z3fold: fix z3fold_page_migrate races with z3fold_map Date: Fri, 29 Apr 2022 14:40:43 +0800 Think about the below scenario: CPU1 CPU2 z3fold_page_migrate z3fold_map z3fold_page_trylock ... z3fold_page_unlock /* slots still points to old zhdr*/ get_z3fold_header get slots from handle get old zhdr from slots z3fold_page_trylock return *old* zhdr encode_handle(new_zhdr, FIRST|LAST|MIDDLE) put_page(page) /* zhdr is freed! */ but zhdr is still used by caller! z3fold_map can map freed z3fold page and lead to use-after-free bug. To fix it, we add PAGE_MIGRATED to indicate z3fold page is migrated and soon to be released. So get_z3fold_header won't return such page. Link: https://lkml.kernel.org/r/20220429064051.61552-10-linmiaohe@huawei.com Fixes: 1f862989b04a ("mm/z3fold.c: support page migration") Signed-off-by: Miaohe Lin Reviewed-by: Vitaly Wool Signed-off-by: Andrew Morton --- mm/z3fold.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) --- a/mm/z3fold.c~mm-z3fold-fix-z3fold_page_migrate-races-with-z3fold_map +++ a/mm/z3fold.c @@ -181,6 +181,7 @@ enum z3fold_page_flags { NEEDS_COMPACTING, PAGE_STALE, PAGE_CLAIMED, /* by either reclaim or free */ + PAGE_MIGRATED, /* page is migrated and soon to be released */ }; /* @@ -270,8 +271,13 @@ static inline struct z3fold_header *get_ zhdr = (struct z3fold_header *)(addr & PAGE_MASK); locked = z3fold_page_trylock(zhdr); read_unlock(&slots->lock); - if (locked) - break; + if (locked) { + struct page *page = virt_to_page(zhdr); + + if (!test_bit(PAGE_MIGRATED, &page->private)) + break; + z3fold_page_unlock(zhdr); + } cpu_relax(); } while (true); } else { @@ -389,6 +395,7 @@ static struct z3fold_header *init_z3fold clear_bit(NEEDS_COMPACTING, &page->private); clear_bit(PAGE_STALE, &page->private); clear_bit(PAGE_CLAIMED, &page->private); + clear_bit(PAGE_MIGRATED, &page->private); if (headless) return zhdr; @@ -1576,7 +1583,7 @@ static int z3fold_page_migrate(struct ad new_zhdr = page_address(newpage); memcpy(new_zhdr, zhdr, PAGE_SIZE); newpage->private = page->private; - page->private = 0; + set_bit(PAGE_MIGRATED, &page->private); z3fold_page_unlock(zhdr); spin_lock_init(&new_zhdr->page_lock); INIT_WORK(&new_zhdr->work, compact_page_work); @@ -1606,7 +1613,8 @@ static int z3fold_page_migrate(struct ad queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work); - clear_bit(PAGE_CLAIMED, &page->private); + /* PAGE_CLAIMED and PAGE_MIGRATED are cleared now. */ + page->private = 0; put_page(page); return 0; } _ Patches currently in -mm which might be from linmiaohe@huawei.com are