From patchwork Mon Jan 17 05:36:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12714758 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 9A1F5C433EF for ; Mon, 17 Jan 2022 05:37:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233240AbiAQFhj (ORCPT ); Mon, 17 Jan 2022 00:37:39 -0500 Received: from smtp-out1.suse.de ([195.135.220.28]:50014 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234419AbiAQFhK (ORCPT ); Mon, 17 Jan 2022 00:37:10 -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 CB9AC2113D; Mon, 17 Jan 2022 05:37:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1642397828; 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=d6hUfGwB2T6XZK7oROCnB/akEcWjBVnpd4biGATOsmo=; b=MLKjA8+oTWdvIqDwiGeDiJAcjEvGV4jxxbnVJADU4PJhLPJnrj25t1wanzG+v/6/wXWdnI nMbLMcDLRInILnVu/kwfLFsGiaLBCOO+FXmDa5H9YB7wZ37qzsvwB1OCKHCc7LPwdlUuYL evR+62Z39tT74ssc7UwA/lsNg/pAb3s= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1642397828; 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=d6hUfGwB2T6XZK7oROCnB/akEcWjBVnpd4biGATOsmo=; b=tkXGt+hNtN/tfTXR5FHQgqHhCbGnl1QiMfFLGAKiP98RXLULpk+MW5E3M9AkMqUDjBbZts /N6+0aggk2P7qEDw== 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 B3C80134AD; Mon, 17 Jan 2022 05:37:07 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 3CXRG4MA5WF1XwAAMHmgww (envelope-from ); Mon, 17 Jan 2022 05:37:07 +0000 MIME-Version: 1.0 From: "NeilBrown" To: "Anna Schumaker" , "'Trond Myklebust'" Cc: "Linux NFS Mailing List" Subject: [PATCH v2] SUNRPC: lock against ->sock changing during sysfs read In-reply-to: <164239753694.24166.6067045930030508953@noble.neil.brown.name> References: <164239753694.24166.6067045930030508953@noble.neil.brown.name> Date: Mon, 17 Jan 2022 16:36:53 +1100 Message-id: <164239781318.24166.18390532919429401983@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 --- Sorry about the v2 - I hadn't noticed that there are two places that need fixing. NeilBrown net/sunrpc/sysfs.c | 5 ++++- net/sunrpc/xprtsock.c | 7 ++++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/sysfs.c b/net/sunrpc/sysfs.c index 2766dd21935b..baaf65ea9e38 100644 --- a/net/sunrpc/sysfs.c +++ b/net/sunrpc/sysfs.c @@ -115,11 +115,14 @@ static ssize_t rpc_sysfs_xprt_srcaddr_show(struct kobject *kobj, } sock = container_of(xprt, struct sock_xprt, xprt); - if (kernel_getsockname(sock->sock, (struct sockaddr *)&saddr) < 0) + mutex_lock(&sock->recv_mutex); + if (sock->sock == NULL || + kernel_getsockname(sock->sock, (struct sockaddr *)&saddr) < 0) goto out; ret = sprintf(buf, "%pISc\n", &saddr); out: + mutex_unlock(&sock->recv_mutex); xprt_put(xprt); return ret + 1; } 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);