From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46A88C64E7A for ; Tue, 17 Nov 2020 13:11:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 05C0E2468F for ; Tue, 17 Nov 2020 13:11:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="iyogoQY7" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729540AbgKQNKv (ORCPT ); Tue, 17 Nov 2020 08:10:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:40144 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728530AbgKQNKs (ORCPT ); Tue, 17 Nov 2020 08:10:48 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 84D1C2468F; Tue, 17 Nov 2020 13:10:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605618647; bh=MyyVrVhxxSxMlX0j11555xj4CT/uRjIwpQ6kpo5EBFI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iyogoQY76u4s3q/d7T18eHTot0ZQO+vhmxorKKr1nfoint8+M6yNxKgItUpa8wVtx YqwhajIM2V1fCGNt8+cYvRp/tcJ32CwlvUbz9WLBeCqcMc5AfYqzEojeuqho0t/D9H IXeRUylfu7M4EEAV1B7m0+HfdObSwAeSobDteMsM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, zhuoliang zhang , Herbert Xu , Steffen Klassert , Sasha Levin Subject: [PATCH 4.9 08/78] net: xfrm: fix a race condition during allocing spi Date: Tue, 17 Nov 2020 14:04:34 +0100 Message-Id: <20201117122109.506212727@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201117122109.116890262@linuxfoundation.org> References: <20201117122109.116890262@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: zhuoliang zhang [ Upstream commit a779d91314ca7208b7feb3ad817b62904397c56d ] we found that the following race condition exists in xfrm_alloc_userspi flow: user thread state_hash_work thread ---- ---- xfrm_alloc_userspi() __find_acq_core() /*alloc new xfrm_state:x*/ xfrm_state_alloc() /*schedule state_hash_work thread*/ xfrm_hash_grow_check() xfrm_hash_resize() xfrm_alloc_spi /*hold lock*/ x->id.spi = htonl(spi) spin_lock_bh(&net->xfrm.xfrm_state_lock) /*waiting lock release*/ xfrm_hash_transfer() spin_lock_bh(&net->xfrm.xfrm_state_lock) /*add x into hlist:net->xfrm.state_byspi*/ hlist_add_head_rcu(&x->byspi) spin_unlock_bh(&net->xfrm.xfrm_state_lock) /*add x into hlist:net->xfrm.state_byspi 2 times*/ hlist_add_head_rcu(&x->byspi) 1. a new state x is alloced in xfrm_state_alloc() and added into the bydst hlist in __find_acq_core() on the LHS; 2. on the RHS, state_hash_work thread travels the old bydst and tranfers every xfrm_state (include x) into the new bydst hlist and new byspi hlist; 3. user thread on the LHS gets the lock and adds x into the new byspi hlist again. So the same xfrm_state (x) is added into the same list_hash (net->xfrm.state_byspi) 2 times that makes the list_hash become an inifite loop. To fix the race, x->id.spi = htonl(spi) in the xfrm_alloc_spi() is moved to the back of spin_lock_bh, sothat state_hash_work thread no longer add x which id.spi is zero into the hash_list. Fixes: f034b5d4efdf ("[XFRM]: Dynamic xfrm_state hash table sizing.") Signed-off-by: zhuoliang zhang Acked-by: Herbert Xu Signed-off-by: Steffen Klassert Signed-off-by: Sasha Levin --- net/xfrm/xfrm_state.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 0eb85765d35a1..4d19f2ff6e052 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -1591,6 +1591,7 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high) int err = -ENOENT; __be32 minspi = htonl(low); __be32 maxspi = htonl(high); + __be32 newspi = 0; u32 mark = x->mark.v & x->mark.m; spin_lock_bh(&x->lock); @@ -1609,21 +1610,22 @@ int xfrm_alloc_spi(struct xfrm_state *x, u32 low, u32 high) xfrm_state_put(x0); goto unlock; } - x->id.spi = minspi; + newspi = minspi; } else { u32 spi = 0; for (h = 0; h < high-low+1; h++) { spi = low + prandom_u32()%(high-low+1); x0 = xfrm_state_lookup(net, mark, &x->id.daddr, htonl(spi), x->id.proto, x->props.family); if (x0 == NULL) { - x->id.spi = htonl(spi); + newspi = htonl(spi); break; } xfrm_state_put(x0); } } - if (x->id.spi) { + if (newspi) { spin_lock_bh(&net->xfrm.xfrm_state_lock); + x->id.spi = newspi; h = xfrm_spi_hash(net, &x->id.daddr, x->id.spi, x->id.proto, x->props.family); hlist_add_head_rcu(&x->byspi, net->xfrm.state_byspi + h); spin_unlock_bh(&net->xfrm.xfrm_state_lock); -- 2.27.0