From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8212C63B8 for ; Mon, 20 Feb 2023 13:53:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A965C433EF; Mon, 20 Feb 2023 13:53:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1676901226; bh=YWED7BKr75/WFBur95Zx0AtVxFD19dmzh5P3McXo8+U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OilPVl60GSmhqiDTjnfbU/uLWdbk39CgO5GSkUQ2hyL510UDIqhJdtEaIV8xZ5wQ6 sD+1Aq5osY36K0nviJMxu/va00Hl1t3lzSR7GJqNgfsj57Wh8uTJHbF2iu+uvBlpf2 u0z36kSv+l4Bf7Kya5272xxPbX/rdJh6JOR9nB5Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, valis , Jamal Hadi Salim , Pedro Tammela , Jakub Kicinski Subject: [PATCH 5.15 60/83] net/sched: tcindex: update imperfect hash filters respecting rcu Date: Mon, 20 Feb 2023 14:36:33 +0100 Message-Id: <20230220133555.769278388@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230220133553.669025851@linuxfoundation.org> References: <20230220133553.669025851@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Pedro Tammela commit ee059170b1f7e94e55fa6cadee544e176a6e59c2 upstream. The imperfect hash area can be updated while packets are traversing, which will cause a use-after-free when 'tcf_exts_exec()' is called with the destroyed tcf_ext. CPU 0: CPU 1: tcindex_set_parms tcindex_classify tcindex_lookup tcindex_lookup tcf_exts_change tcf_exts_exec [UAF] Stop operating on the shared area directly, by using a local copy, and update the filter with 'rcu_replace_pointer()'. Delete the old filter version only after a rcu grace period elapsed. Fixes: 9b0d4446b569 ("net: sched: avoid atomic swap in tcf_exts_change") Reported-by: valis Suggested-by: valis Signed-off-by: Jamal Hadi Salim Signed-off-by: Pedro Tammela Link: https://lore.kernel.org/r/20230209143739.279867-1-pctammela@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/sched/cls_tcindex.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) --- a/net/sched/cls_tcindex.c +++ b/net/sched/cls_tcindex.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -338,6 +339,7 @@ tcindex_set_parms(struct net *net, struc struct tcf_result cr = {}; int err, balloc = 0; struct tcf_exts e; + bool update_h = false; err = tcf_exts_init(&e, net, TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE); if (err < 0) @@ -455,10 +457,13 @@ tcindex_set_parms(struct net *net, struc } } - if (cp->perfect) + if (cp->perfect) { r = cp->perfect + handle; - else - r = tcindex_lookup(cp, handle) ? : &new_filter_result; + } else { + /* imperfect area is updated in-place using rcu */ + update_h = !!tcindex_lookup(cp, handle); + r = &new_filter_result; + } if (r == &new_filter_result) { f = kzalloc(sizeof(*f), GFP_KERNEL); @@ -484,7 +489,28 @@ tcindex_set_parms(struct net *net, struc rcu_assign_pointer(tp->root, cp); - if (r == &new_filter_result) { + if (update_h) { + struct tcindex_filter __rcu **fp; + struct tcindex_filter *cf; + + f->result.res = r->res; + tcf_exts_change(&f->result.exts, &r->exts); + + /* imperfect area bucket */ + fp = cp->h + (handle % cp->hash); + + /* lookup the filter, guaranteed to exist */ + for (cf = rcu_dereference_bh_rtnl(*fp); cf; + fp = &cf->next, cf = rcu_dereference_bh_rtnl(*fp)) + if (cf->key == handle) + break; + + f->next = cf->next; + + cf = rcu_replace_pointer(*fp, f, 1); + tcf_exts_get_net(&cf->result.exts); + tcf_queue_work(&cf->rwork, tcindex_destroy_fexts_work); + } else if (r == &new_filter_result) { struct tcindex_filter *nfp; struct tcindex_filter __rcu **fp;