From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932504Ab1HFAM7 (ORCPT ); Fri, 5 Aug 2011 20:12:59 -0400 Received: from cantor2.suse.de ([195.135.220.15]:39842 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932490Ab1HFAMz (ORCPT ); Fri, 5 Aug 2011 20:12:55 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Fri Aug 5 17:04:15 2011 Message-Id: <20110806000415.231907014@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Fri, 05 Aug 2011 17:03:54 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, gnb@fmeh.org, "J. Bruce Fields" Subject: [36/50] svcrpc: fix list-corrupting race on nfsd shutdown In-Reply-To: <20110806000419.GA28392@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.33-longterm review patch. If anyone has any objections, please let us know. ------------------ From: "J. Bruce Fields" commit ebc63e531cc6a457595dd110b07ac530eae788c3 upstream. After commit 3262c816a3d7fb1eaabce633caa317887ed549ae "[PATCH] knfsd: split svc_serv into pools", svc_delete_xprt (then svc_delete_socket) no longer removed its xpt_ready (then sk_ready) field from whatever list it was on, noting that there was no point since the whole list was about to be destroyed anyway. That was mostly true, but forgot that a few svc_xprt_enqueue()'s might still be hanging around playing with the about-to-be-destroyed list, and could get themselves into trouble writing to freed memory if we left this xprt on the list after freeing it. (This is actually functionally identical to a patch made first by Ben Greear, but with more comments.) Cc: gnb@fmeh.org Reported-by: Ben Greear Tested-by: Ben Greear Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/svc_xprt.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -884,12 +884,13 @@ void svc_delete_xprt(struct svc_xprt *xp if (!test_and_set_bit(XPT_DETACHED, &xprt->xpt_flags)) list_del_init(&xprt->xpt_list); /* - * We used to delete the transport from whichever list - * it's sk_xprt.xpt_ready node was on, but we don't actually - * need to. This is because the only time we're called - * while still attached to a queue, the queue itself - * is about to be destroyed (in svc_destroy). + * The only time we're called while xpt_ready is still on a list + * is while the list itself is about to be destroyed (in + * svc_destroy). BUT svc_xprt_enqueue could still be attempting + * to add new entries to the sp_sockets list, so we can't leave + * a freed xprt on it. */ + list_del_init(&xprt->xpt_ready); if (test_bit(XPT_TEMP, &xprt->xpt_flags)) serv->sv_tmpcnt--;