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 4D39215E83 for ; Mon, 23 Oct 2023 11:37:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Fb/GV/tY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC67EC433C8; Mon, 23 Oct 2023 11:37:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1698061079; bh=oaRjAazGyl1/avvZs1MOoIFq3ZfC3XwFC8SRFCMTRbY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Fb/GV/tY7hNqeP67+mi6l+CwpEH8KD5hh16S8pKaXjCRklZPb8SzyR83WuWn5n+XK XFp8ZzWIz7cI5YuSn12FnkFZDElFpQe1bHYd+oIOw2VJ9fIWPgERPtVzJVm+im7Z19 07pTGfmoBo9SLYsXiIWHfCUYin6ibg46ipZ4C/Fc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sili Luo , Jeremy Kerr , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.15 065/137] mctp: perform route lookups under a RCU read-side lock Date: Mon, 23 Oct 2023 12:57:02 +0200 Message-ID: <20231023104823.153083742@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231023104820.849461819@linuxfoundation.org> References: <20231023104820.849461819@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeremy Kerr [ Upstream commit 5093bbfc10ab6636b32728e35813cbd79feb063c ] Our current route lookups (mctp_route_lookup and mctp_route_lookup_null) traverse the net's route list without the RCU read lock held. This means the route lookup is subject to preemption, resulting in an potential grace period expiry, and so an eventual kfree() while we still have the route pointer. Add the proper read-side critical section locks around the route lookups, preventing premption and a possible parallel kfree. The remaining net->mctp.routes accesses are already under a rcu_read_lock, or protected by the RTNL for updates. Based on an analysis from Sili Luo , where introducing a delay in the route lookup could cause a UAF on simultaneous sendmsg() and route deletion. Reported-by: Sili Luo Fixes: 889b7da23abf ("mctp: Add initial routing framework") Cc: stable@vger.kernel.org Signed-off-by: Jeremy Kerr Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/29c4b0e67dc1bf3571df3982de87df90cae9b631.1696837310.git.jk@codeconstruct.com.au Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/mctp/route.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/net/mctp/route.c b/net/mctp/route.c index 859f57fd3871f..5ef6b3b0a3d99 100644 --- a/net/mctp/route.c +++ b/net/mctp/route.c @@ -549,6 +549,8 @@ struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, { struct mctp_route *tmp, *rt = NULL; + rcu_read_lock(); + list_for_each_entry_rcu(tmp, &net->mctp.routes, list) { /* TODO: add metrics */ if (mctp_rt_match_eid(tmp, dnet, daddr)) { @@ -559,21 +561,29 @@ struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, } } + rcu_read_unlock(); + return rt; } static struct mctp_route *mctp_route_lookup_null(struct net *net, struct net_device *dev) { - struct mctp_route *rt; + struct mctp_route *tmp, *rt = NULL; - list_for_each_entry_rcu(rt, &net->mctp.routes, list) { - if (rt->dev->dev == dev && rt->type == RTN_LOCAL && - refcount_inc_not_zero(&rt->refs)) - return rt; + rcu_read_lock(); + + list_for_each_entry_rcu(tmp, &net->mctp.routes, list) { + if (tmp->dev->dev == dev && tmp->type == RTN_LOCAL && + refcount_inc_not_zero(&tmp->refs)) { + rt = tmp; + break; + } } - return NULL; + rcu_read_unlock(); + + return rt; } /* sends a skb to rt and releases the route. */ -- 2.40.1