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[2620:137:e000::1:20]) by mx.google.com with ESMTP id h2-20020aa79f42000000b004fa6cbcbbf0si12221257pfr.235.2022.03.27.23.29.49; Sun, 27 Mar 2022 23:30:16 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=j20HQM2N; spf=pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-nfs-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229689AbiC0IEV (ORCPT + 99 others); Sun, 27 Mar 2022 04:04:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51562 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229636AbiC0IEV (ORCPT ); Sun, 27 Mar 2022 04:04:21 -0400 Received: from mail-pf1-x430.google.com (mail-pf1-x430.google.com [IPv6:2607:f8b0:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A401D43AC7; Sun, 27 Mar 2022 01:02:39 -0700 (PDT) Received: by mail-pf1-x430.google.com with SMTP id f3so8723085pfe.2; Sun, 27 Mar 2022 01:02:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id; bh=6WEcIiDLKxrIOj61KNbQv+CB44nK63wxSMiAxjt7pBc=; b=j20HQM2NdRCFaPujnXUn9LlRirzydADGi+yfn8XMf826iiWVvT8KRXsx/KsUnpTdQh e/oNsy+o00PBQWzDLRcPBmQ6h1X3TY3hgddH8q17c207+CiGOJZaXhBIq2QE4lreL1Vr FpAIpq2V2QJ1wRqsSgBeN8OHzPlJErp4W+tWe24ecsIs1/AqPtkXZ0QJR+1UGVmUkkcG m82t5HFIAZFkavuA6d4OZy+AKzi3JQ2qofj065KQYZzrmhM1miV0lKo3GEt+2/NDMoYZ OOBOaw5d0/uFHCsA/VXz/zPF61Csaaw+PnkFJakyCrgBdSDLPySujfQaD34MSDjZMsat igVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=6WEcIiDLKxrIOj61KNbQv+CB44nK63wxSMiAxjt7pBc=; b=Dc1Xo7bXMK8xAtRjbJA+USVFlfCqp+oEmMsIkNaz6UHaSxp4YTksyALG88WUSOrAWy SAzREpqaP4T6O13xdv+RPXfVRZ11Pi5tC7zpR39RKuMWJJ3mhUD9UDlo9d5SWWewrjWw Fy9CrMJtLq0C9mFOJUQWsN+xxMDpGqZNUCQ7aJMiR/sK1JFcS8HkUqtp7yB5AEVhqgS8 RaHjl9zeF9b30t8hYW1hAIRGTD05B4yYt8I21UiVX9qw9mwx6ugqI6qvtmPVSqIMrCuv /uzdUXB0xdnZxRRksCa2EOudSg/lm4o37oSQUHFZqi7S9+p8voC+WZ1F1q0BD1uZrMto rdBA== X-Gm-Message-State: AOAM530EB8xDbb/BSJwfkjNbWxHI8TomqJC9P1nm9KXzfY5tN1g6vFD/ 0KlxVs+crE6OvAxGR/G8pRo= X-Received: by 2002:a63:fd01:0:b0:381:31b7:8bc5 with SMTP id d1-20020a63fd01000000b0038131b78bc5mr5928177pgh.206.1648368158572; Sun, 27 Mar 2022 01:02:38 -0700 (PDT) Received: from localhost ([115.220.243.108]) by smtp.gmail.com with ESMTPSA id i6-20020a633c46000000b003817d623f72sm9744595pgn.24.2022.03.27.01.02.37 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Sun, 27 Mar 2022 01:02:38 -0700 (PDT) From: Xiaomeng Tong To: trond.myklebust@hammerspace.com, anna@kernel.org Cc: bhalevy@panasas.com, bharrosh@panasas.com, linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaomeng Tong , stable@vger.kernel.org Subject: [PATCH] nfs: callback_proc: fix an incorrect NULL check on list iterator Date: Sun, 27 Mar 2022 16:02:30 +0800 Message-Id: <20220327080230.12134-1-xiam0nd.tong@gmail.com> X-Mailer: git-send-email 2.17.1 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org The bug is here: if (!server || server->pnfs_curr_ld->id != dev->cbd_layout_type) { The list iterator value 'server' will *always* be set and non-NULL by list_for_each_entry_rcu, so it is incorrect to assume that the iterator value will be NULL if the list is empty or no element is found (In fact, it will be a bogus pointer to an invalid struct object containing the HEAD, which is used for above check at next outer loop). Otherwise it may bypass the check in theory (iif server->pnfs_curr_ld->id == dev->cbd_layout_type, 'server' now is a bogus pointer) and lead to invalid memory access passing the check. To fix the bug, use a new variable 'iter' as the list iterator, while use the original variable 'server' as a dedicated pointer to point to the found element. Cc: stable@vger.kernel.org Fixes: 1be5683b03a76 ("pnfs: CB_NOTIFY_DEVICEID") Signed-off-by: Xiaomeng Tong --- fs/nfs/callback_proc.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c index c343666d9a42..84779785dc8d 100644 --- a/fs/nfs/callback_proc.c +++ b/fs/nfs/callback_proc.c @@ -361,7 +361,7 @@ __be32 nfs4_callback_devicenotify(void *argp, void *resp, uint32_t i; __be32 res = 0; struct nfs_client *clp = cps->clp; - struct nfs_server *server = NULL; + struct nfs_server *server = NULL, *iter; if (!clp) { res = cpu_to_be32(NFS4ERR_OP_NOT_IN_SESSION); @@ -374,10 +374,11 @@ __be32 nfs4_callback_devicenotify(void *argp, void *resp, if (!server || server->pnfs_curr_ld->id != dev->cbd_layout_type) { rcu_read_lock(); - list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) - if (server->pnfs_curr_ld && - server->pnfs_curr_ld->id == dev->cbd_layout_type) { + list_for_each_entry_rcu(iter, &clp->cl_superblocks, client_link) + if (iter->pnfs_curr_ld && + iter->pnfs_curr_ld->id == dev->cbd_layout_type) { rcu_read_unlock(); + server = iter; goto found; } rcu_read_unlock(); -- 2.17.1