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 3422728DBA for ; Mon, 16 Oct 2023 14:54:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="o/eJys2R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75DDFC433C8; Mon, 16 Oct 2023 14:54:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1697468095; bh=Q54hp2hObsp8vY/3Cn8TWqc+1e1twjm1g2apDI9yxOo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o/eJys2RJdBnlyEv4x3/8C7Q0rQQgnRWa/6U+fR5I0dYaKvGumUESebb8ezwGVKnc lQVIghKc67PIXyOQcNShW/HceM7WV47Uufx6INhC74iU3cUS8LwcGLsxgIivsAKgDu /Ptve2RuTpupkkX3++JABOI6WO3UdOpVSk5EtvX0= 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 Subject: [PATCH 6.5 156/191] mctp: perform route lookups under a RCU read-side lock Date: Mon, 16 Oct 2023 10:42:21 +0200 Message-ID: <20231016084019.017021106@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231016084015.400031271@linuxfoundation.org> References: <20231016084015.400031271@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 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeremy Kerr commit 5093bbfc10ab6636b32728e35813cbd79feb063c upstream. 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: Greg Kroah-Hartman --- net/mctp/route.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) --- a/net/mctp/route.c +++ b/net/mctp/route.c @@ -737,6 +737,8 @@ struct mctp_route *mctp_route_lookup(str { 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)) { @@ -747,21 +749,29 @@ struct mctp_route *mctp_route_lookup(str } } + 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; + + rcu_read_lock(); - 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; + 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; } static int mctp_do_fragment_route(struct mctp_route *rt, struct sk_buff *skb,