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 60D4DC77B75 for ; Mon, 15 May 2023 17:55:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237835AbjEORzQ (ORCPT ); Mon, 15 May 2023 13:55:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241787AbjEORyf (ORCPT ); Mon, 15 May 2023 13:54:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 02DEB183FE for ; Mon, 15 May 2023 10:52:35 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 76A5A62F92 for ; Mon, 15 May 2023 17:51:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61AA5C433D2; Mon, 15 May 2023 17:51:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684173075; bh=Gf5vcxUqVMXCCfZA7pUAKHw/feiI8+HhUqgKVzG2U3U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dcb+nCcTaw7w8rZ7dDLFNQn0fiLGO6aopkpGEIGDPlAJONjzUXJVa6MWfP0JsCtMg fvlI7y/P8qdc0OMUJ40FleNyrOO0hrjzGWjJHqZVpQ9kycSgOOMDtFkfpq6J8and0c SMXbC5arxnPaRgMV7fKgijOf7Y2xH0WLFxyH7x+I= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, syzbot+4a03518df1e31b537066@syzkaller.appspotmail.com, Dmitry Vyukov , Jan Kara , Theodore Tso Subject: [PATCH 5.10 360/381] ext4: fix data races when using cached status extents Date: Mon, 15 May 2023 18:30:11 +0200 Message-Id: <20230515161753.165129609@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161736.775969473@linuxfoundation.org> References: <20230515161736.775969473@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jan Kara commit 492888df0c7b42fc0843631168b0021bc4caee84 upstream. When using cached extent stored in extent status tree in tree->cache_es another process holding ei->i_es_lock for reading can be racing with us setting new value of tree->cache_es. If the compiler would decide to refetch tree->cache_es at an unfortunate moment, it could result in a bogus in_range() check. Fix the possible race by using READ_ONCE() when using tree->cache_es only under ei->i_es_lock for reading. Cc: stable@kernel.org Reported-by: syzbot+4a03518df1e31b537066@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/000000000000d3b33905fa0fd4a6@google.com Suggested-by: Dmitry Vyukov Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20230504125524.10802-1-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/extents_status.c | 30 +++++++++++++----------------- 1 file changed, 13 insertions(+), 17 deletions(-) --- a/fs/ext4/extents_status.c +++ b/fs/ext4/extents_status.c @@ -269,14 +269,12 @@ static void __es_find_extent_range(struc /* see if the extent has been cached */ es->es_lblk = es->es_len = es->es_pblk = 0; - if (tree->cache_es) { - es1 = tree->cache_es; - if (in_range(lblk, es1->es_lblk, es1->es_len)) { - es_debug("%u cached by [%u/%u) %llu %x\n", - lblk, es1->es_lblk, es1->es_len, - ext4_es_pblock(es1), ext4_es_status(es1)); - goto out; - } + es1 = READ_ONCE(tree->cache_es); + if (es1 && in_range(lblk, es1->es_lblk, es1->es_len)) { + es_debug("%u cached by [%u/%u) %llu %x\n", + lblk, es1->es_lblk, es1->es_len, + ext4_es_pblock(es1), ext4_es_status(es1)); + goto out; } es1 = __es_tree_search(&tree->root, lblk); @@ -295,7 +293,7 @@ out: } if (es1 && matching_fn(es1)) { - tree->cache_es = es1; + WRITE_ONCE(tree->cache_es, es1); es->es_lblk = es1->es_lblk; es->es_len = es1->es_len; es->es_pblk = es1->es_pblk; @@ -934,14 +932,12 @@ int ext4_es_lookup_extent(struct inode * /* find extent in cache firstly */ es->es_lblk = es->es_len = es->es_pblk = 0; - if (tree->cache_es) { - es1 = tree->cache_es; - if (in_range(lblk, es1->es_lblk, es1->es_len)) { - es_debug("%u cached by [%u/%u)\n", - lblk, es1->es_lblk, es1->es_len); - found = 1; - goto out; - } + es1 = READ_ONCE(tree->cache_es); + if (es1 && in_range(lblk, es1->es_lblk, es1->es_len)) { + es_debug("%u cached by [%u/%u)\n", + lblk, es1->es_lblk, es1->es_len); + found = 1; + goto out; } node = tree->root.rb_node;