From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:42224 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753624AbcA0G3H (ORCPT ); Wed, 27 Jan 2016 01:29:07 -0500 Subject: Patch "batman-adv: Avoid recursive call_rcu for batadv_bla_claim" has been added to the 4.1-stable tree To: sven@narfation.org, a@unstable.cc, gregkh@linuxfoundation.org, mareklindner@neomailbox.ch, sw@simonwunderlich.de Cc: , From: Date: Tue, 26 Jan 2016 22:27:36 -0800 Message-ID: <145387605687103@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled batman-adv: Avoid recursive call_rcu for batadv_bla_claim to the 4.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: batman-adv-avoid-recursive-call_rcu-for-batadv_bla_claim.patch and it can be found in the queue-4.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo@baz Tue Jan 26 21:37:04 PST 2016 From: Sven Eckelmann Date: Thu, 14 Jan 2016 15:28:19 +0100 Subject: batman-adv: Avoid recursive call_rcu for batadv_bla_claim From: Sven Eckelmann [ Upstream commit 63b399272294e7a939cde41792dca38c549f0484 ] The batadv_claim_free_ref function uses call_rcu to delay the free of the batadv_bla_claim object until no (already started) rcu_read_lock is enabled anymore. This makes sure that no context is still trying to access the object which should be removed. But batadv_bla_claim also contains a reference to backbone_gw which must be removed. The reference drop of backbone_gw was done in the call_rcu function batadv_claim_free_rcu but should actually be done in the batadv_claim_release function to avoid nested call_rcus. This is important because rcu_barrier (e.g. batadv_softif_free or batadv_exit) will not detect the inner call_rcu as relevant for its execution. Otherwise this barrier will most likely be inserted in the queue before the callback of the first call_rcu was executed. The caller of rcu_barrier will therefore continue to run before the inner call_rcu callback finished. Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Signed-off-by: Sven Eckelmann Acked-by: Simon Wunderlich Signed-off-by: Marek Lindner Signed-off-by: Antonio Quartulli Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/bridge_loop_avoidance.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -112,21 +112,17 @@ batadv_backbone_gw_free_ref(struct batad } /* finally deinitialize the claim */ -static void batadv_claim_free_rcu(struct rcu_head *rcu) +static void batadv_claim_release(struct batadv_bla_claim *claim) { - struct batadv_bla_claim *claim; - - claim = container_of(rcu, struct batadv_bla_claim, rcu); - batadv_backbone_gw_free_ref(claim->backbone_gw); - kfree(claim); + kfree_rcu(claim, rcu); } /* free a claim, call claim_free_rcu if its the last reference */ static void batadv_claim_free_ref(struct batadv_bla_claim *claim) { if (atomic_dec_and_test(&claim->refcount)) - call_rcu(&claim->rcu, batadv_claim_free_rcu); + batadv_claim_release(claim); } /** Patches currently in stable-queue which might be from sven@narfation.org are queue-4.1/batman-adv-drop-immediate-batadv_neigh_node-free-function.patch queue-4.1/batman-adv-drop-immediate-neigh_ifinfo-free-function.patch queue-4.1/batman-adv-drop-immediate-orig_node-free-function.patch queue-4.1/batman-adv-drop-immediate-batadv_orig_ifinfo-free-function.patch queue-4.1/batman-adv-avoid-recursive-call_rcu-for-batadv_nc_node.patch queue-4.1/batman-adv-drop-immediate-batadv_hard_iface-free-function.patch queue-4.1/batman-adv-avoid-recursive-call_rcu-for-batadv_bla_claim.patch