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 C3B17C433EF for ; Tue, 25 Jan 2022 03:10:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1317501AbiAYDCO (ORCPT ); Mon, 24 Jan 2022 22:02:14 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:47120 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S3415321AbiAYBmj (ORCPT ); Mon, 24 Jan 2022 20:42:39 -0500 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 2AC34219A2; Tue, 25 Jan 2022 01:26:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1643073984; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ukdL4uSY7ajaeLLyOy2K7g+OJNEsLFNzoe0K6HxbbBg=; b=BwXWmNKUWNf/QWwndBHhxlD2Xpth4f7ipnaSxOD2XBfHipf1jgH6D0R2Spb2M3qCWIYW6m x8HgPaGGvhDhmCSwpUrMVDzLVO3WKJuln+opQ2oqurTLT2CirjYFmmlkxIvnmpobc9OcMr /XVRrjkS2Bwcj0UP8GK7CtnWdspz7kU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1643073984; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ukdL4uSY7ajaeLLyOy2K7g+OJNEsLFNzoe0K6HxbbBg=; b=l73U2zJamff6zF7815X4J+N8Rh0uBqiHROilqBddtxvC5Hb7ncpUxcTc2cZAgSaKaR9EEQ EVSFagbOQhELLeDw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id EA36B13B08; Tue, 25 Jan 2022 01:26:22 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id aIQzLb5R72HYGQAAMHmgww (envelope-from ); Tue, 25 Jan 2022 01:26:22 +0000 Message-ID: Date: Tue, 25 Jan 2022 09:26:21 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH] bcache: Fix a NULL or wild pointer dereference in btree_gc_rewrite_node() Content-Language: en-US To: Zhou Qingyang Cc: kjlu@umn.edu, Kent Overstreet , linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220124164701.53525-1-zhou1615@umn.edu> From: Coly Li In-Reply-To: <20220124164701.53525-1-zhou1615@umn.edu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/25/22 12:47 AM, Zhou Qingyang wrote: > In btree_gc_rewrite_node(), btree_node_alloc_replacement() is assigned to > n and return error code or NULL on failure. n is passed to > bch_btree_node_write_sync() and there is a dereference of it in > bch_btree_node_write_sync() without checks, which may lead to wild > pointer dereference or NULL pointer dereference depending on n. > > Fix this bug by adding IS_ERR_OR_NULL check of n. > > This bug was found by a static analyzer. > > Builds with 'make allyesconfig' show no new warnings, > and our static analyzer no longer warns about this code. > > Fixes: ("bcache: Rework btree cache reserve handling") > Signed-off-by: Zhou Qingyang > --- > The analysis employs differential checking to identify inconsistent > security operations (e.g., checks or kfrees) between two code paths > and confirms that the inconsistent operations are not recovered in the > current function or the callers, so they constitute bugs. > > Note that, as a bug found by static analysis, it can be a false > positive or hard to trigger. Multiple researchers have cross-reviewed > the bug. > > drivers/md/bcache/btree.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c > index 88c573eeb598..06d42292e86c 100644 > --- a/drivers/md/bcache/btree.c > +++ b/drivers/md/bcache/btree.c > @@ -1504,6 +1504,8 @@ static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op, > return 0; > > n = btree_node_alloc_replacement(replace, NULL); > + if (IS_ERR_OR_NULL(n)) > + return 0; > Hi Qingyang, This is a valid fix with my first glance. I add this patch into my testing queue. Thanks. Coly Li > /* recheck reserve after allocating replacement node */ > if (btree_check_reserve(b, NULL)) {