From patchwork Mon Jan 17 05:32:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12714757 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 397F2C433F5 for ; Mon, 17 Jan 2022 05:32:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231936AbiAQFcX (ORCPT ); Mon, 17 Jan 2022 00:32:23 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:49860 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231935AbiAQFcW (ORCPT ); Mon, 17 Jan 2022 00:32:22 -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 8B76F212C4; Mon, 17 Jan 2022 05:32:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1642397541; 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; bh=IXWqcj6mgh2grqkHruNd87w8lgUweF5/uQAMw17Tiaw=; b=c11E/8iK8+Xv+MPv8rjEmVlY4vYgjcsR92j09Qpzuj/6XoduoZrTndS5LzBX/sQNgUHPur wzLiQx5/TnQG/08Pd1Rpte9hGHmWNSf+ytnpWgVUhgx+mlXGPFP9vyUXHNYVcKRH/HYHdc ltjtGUW2u7rw5QCpgH3zX1X5AS8gkIM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1642397541; 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; bh=IXWqcj6mgh2grqkHruNd87w8lgUweF5/uQAMw17Tiaw=; b=Lmru8IZ5FMyhtSY4IRdhf+NzEBQHIiK/S45yQQUYk+BabMHkkZD1cLtyYXFpNlQa+gE7ss OPnx4HTjFElJdvCg== 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 715F1134AD; Mon, 17 Jan 2022 05:32:20 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id SoScC2T/5GFAXgAAMHmgww (envelope-from ); Mon, 17 Jan 2022 05:32:20 +0000 MIME-Version: 1.0 From: "NeilBrown" To: Anna Schumaker , 'Trond Myklebust' Cc: Linux NFS Mailing List Subject: [PATCH] SUNRPC: lock against ->sock changing during sysfs read Date: Mon, 17 Jan 2022 16:32:16 +1100 Message-id: <164239753694.24166.6067045930030508953@noble.neil.brown.name> Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org ->sock can be set to NULL asynchronously unless ->recv_mutex is held. So it is important to hold that mutex. Otherwise a sysfs read can trigger an oops. Commit 17f09d3f619a ("SUNRPC: Check if the xprt is connected before handling sysfs reads") appears to attempt to fix this problem, but it only narrows the race window. Fixes: 17f09d3f619a ("SUNRPC: Check if the xprt is connected before handling sysfs reads") Fixes: a8482488a7d6 ("SUNRPC query transport's source port") Signed-off-by: NeilBrown --- net/sunrpc/xprtsock.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 9d34c71004fa..3f2b766e9f82 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1641,7 +1641,12 @@ static int xs_get_srcport(struct sock_xprt *transport) unsigned short get_srcport(struct rpc_xprt *xprt) { struct sock_xprt *sock = container_of(xprt, struct sock_xprt, xprt); - return xs_sock_getport(sock->sock); + unsigned short ret = 0; + mutex_lock(&sock->recv_mutex); + if (sock->sock) + ret = xs_sock_getport(sock->sock); + mutex_unlock(&sock->recv_mutex); + return ret; } EXPORT_SYMBOL(get_srcport);