From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 783194FC8E6; Wed, 30 Sep 2026 15:46:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790783213; cv=none; b=ErdLiWzXrICn+zPX8FhmUfVBCuLtzxJ7+Npv66ze9oEfn9ghM5dtJ74NWksRfL057ErGIxagFc+1gODUCy8FxHgC3QFIlyz4Q/1SmKnVWId2YH/ab+cVhS59Tu5C0WUhMq/5EUEI0Ky/zyt3M+SX2l2uszmkDVAFZfV8rwtC5GI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790783213; c=relaxed/simple; bh=rlEyaGTH0TGfAzTxd0UwJaKiTvWp06nvUuZ2O7G1WsE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gnN1td1bA2UwHaMb9FMxwFVdb/euXLupiwMlzxNTAsJ9ovKr2cVOGxrJmxLotnAjlOKGbYeKJcYK2eN3ClA9+xq8fpnRnqfFh3dhMSRvcmUXtbtuQ5VPkf4EgjmXJ40G8Ir9fVLTogrY0/3J6VYEaQ9V85iBDMBBqxnUprzXZYw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Nnu2Hd/x; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Nnu2Hd/x" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B3E31F000FF; Wed, 30 Sep 2026 15:46:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790783211; bh=giwyrOY2CkwlvMLJ28/tUDi+9FTKzCeN9s3+INRWJzA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Nnu2Hd/xn77qMap93Jtnbs+wNwBuReyo7oneit/8Wl7AoqCt40Qu3LDI7pzbVTOBM JU2GaH6OEG1XvueMtNzkBcKL9fwwPU43DWYwVHEXJNzhxINBQ/GvfjpDbi12/f1s/Y 1eQyJqgPy+calS0o1vUdW08dqDK4poan/o6e2/us= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , David Ahern , Kuniyuki Iwashima , Jakub Kicinski , Shun Ota , Sasha Levin Subject: [PATCH 5.10 320/595] ipv6: mcast: extend RCU protection in igmp6_send() Date: Wed, 30 Sep 2026 17:23:33 +0200 Message-ID: <20260930152354.569496635@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152347.700140858@linuxfoundation.org> References: <20260930152347.700140858@linuxfoundation.org> User-Agent: quilt/0.69 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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 087c1faa594fa07a66933d750c0b2610aa1a2946 ] igmp6_send() can be called without RTNL or RCU being held. Extend RCU protection so that we can safely fetch the net pointer and avoid a potential UAF. Note that we no longer can use sock_alloc_send_skb() because ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep. Instead use alloc_skb() and charge the net->ipv6.igmp_sk socket under RCU protection. Fixes: b8ad0cbc58f7 ("[NETNS][IPV6] mcast - handle several network namespace") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250207135841.1948589-9-edumazet@google.com Signed-off-by: Jakub Kicinski [ use IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, full_len) instead of upstream's IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTPKTS). Older LTS kernels do not have commit b4a11b2033b7 ("net: fix IPSTATS_MIB_OUTPKGS increment in OutForwDatagrams"), so the legacy byte-based counter logic must be preserved. ] Signed-off-by: Shun Ota Signed-off-by: Sasha Levin --- net/ipv6/mcast.c | 32 +++++++++++++++----------------- 1 file changed, 15 insertions(+), 17 deletions(-) diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index c4a9866ea45b6..7b141c227eefd 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -2146,21 +2146,21 @@ static void mld_send_cr(struct inet6_dev *idev) static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type) { - struct net *net = dev_net(dev); - struct sock *sk = net->ipv6.igmp_sk; + const struct in6_addr *snd_addr, *saddr; + int err, len, payload_len, full_len; + struct in6_addr addr_buf; struct inet6_dev *idev; struct sk_buff *skb; struct mld_msg *hdr; - const struct in6_addr *snd_addr, *saddr; - struct in6_addr addr_buf; int hlen = LL_RESERVED_SPACE(dev); int tlen = dev->needed_tailroom; - int err, len, payload_len, full_len; u8 ra[8] = { IPPROTO_ICMPV6, 0, IPV6_TLV_ROUTERALERT, 2, 0, 0, IPV6_TLV_PADN, 0 }; - struct flowi6 fl6; struct dst_entry *dst; + struct flowi6 fl6; + struct net *net; + struct sock *sk; if (type == ICMPV6_MGM_REDUCTION) snd_addr = &in6addr_linklocal_allrouters; @@ -2171,20 +2171,21 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type) payload_len = len + sizeof(ra); full_len = sizeof(struct ipv6hdr) + payload_len; - rcu_read_lock(); - IP6_UPD_PO_STATS(net, __in6_dev_get(dev), - IPSTATS_MIB_OUT, full_len); - rcu_read_unlock(); + skb = alloc_skb(hlen + tlen + full_len, GFP_KERNEL); - skb = sock_alloc_send_skb(sk, hlen + tlen + full_len, 1, &err); + rcu_read_lock(); + net = dev_net_rcu(dev); + idev = __in6_dev_get(dev); + IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, full_len); if (!skb) { - rcu_read_lock(); - IP6_INC_STATS(net, __in6_dev_get(dev), - IPSTATS_MIB_OUTDISCARDS); + IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); rcu_read_unlock(); return; } + sk = net->ipv6.igmp_sk; + skb_set_owner_w(skb, sk); + skb->priority = TC_PRIO_CONTROL; skb_reserve(skb, hlen); @@ -2209,9 +2210,6 @@ static void igmp6_send(struct in6_addr *addr, struct net_device *dev, int type) IPPROTO_ICMPV6, csum_partial(hdr, len, 0)); - rcu_read_lock(); - idev = __in6_dev_get(skb->dev); - icmpv6_flow_init(sk, &fl6, type, &ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr, skb->dev->ifindex); -- 2.53.0