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 510E55947FF for ; Tue, 8 Sep 2026 17:25:34 +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=1788888335; cv=none; b=nsAur9OtkLIQ5NRchkUU+2i/LYwytdOEJetL5NmnKsyxBNd1uiD/u9p5IeGtH9bBma+sKwvmgJtf+j2JDmMZbRlbWsnv6sZIkccmUdY3de0IHln7CiXR/BrPbwkTGJ6VVi5uxVGiLvVGXZ8T7i4JS6E5wIfaV59hgG7rybU2lg0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788888335; c=relaxed/simple; bh=KLHMjw0HNy76BmKOiktrQOZo8euNdrXQCWk7Du4xjPY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TS0BzQKkNg6KlkIOdWHhvmh1M9ZiyiePpscET8DAxlzhHSygczNwdl1Uq9dhH2AzDjbGpcRAeS7/DP8S8dWccfoalm4Q+hZKOFk+C5EpY7Y5Ox43pyB17nXeNJ+XiBwPkbPCVf2vlNx0OGeFJcDlBjh+WQE5Z5cccm9gGbt/ABs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DNKyUQ5T; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DNKyUQ5T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A1F01F00A3E; Tue, 8 Sep 2026 17:25:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788888333; bh=0KCDyGA7RZpCxAdkTPfbAWayDggP6gx2yaUYI/z/48k=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DNKyUQ5T0fmFMyL+tnhfnCe2Wcql4/EHcvvNs7o5BF7RcN37Y4BoMeYTHg/k23K/8 FjdzRQ7aEBK7aFGJBqjloON9ow9EIv2WPWRS9pP/r/kno97+Sk5tRHVSdlO7USj2Hr K3oVwOdld2UAfjUgedmg7zOZOujxnv3tF0JRctBaUExryvAZlGUvZE+DEgm9MOZXpm vs3czl3q5V//Ld3OCanu4VJLo6xYSA5Fecwbou5dVvdHqAeI0xksE+ovz6TbS3iYt5 BoC65QpgwvEcw5UpMZsxNENxz3ftkWL4JYiCwmQPkYb3TqzCn4/J53gpasoHmtQcXi AaJgBHBVIj8zw== From: Sasha Levin To: stable@vger.kernel.org Cc: Zhiling Zou , Vega , Ido Schimmel , Paolo Abeni , Sasha Levin Subject: [PATCH 6.12.y 3/3] ip: orphan prefetched skbs before multicast forwarding Date: Tue, 8 Sep 2026 13:25:29 -0400 Message-ID: <20260908172529.78857-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908172529.78857-1-sashal@kernel.org> References: <2026090318-afterglow-hash-e60c@gregkh> <20260908172529.78857-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Zhiling Zou [ Upstream commit e36ce6e78fe3fc3c071a26750783b7ba081ce10d ] IPv4 and IPv6 input preserve an skb->sk association installed by bpf_sk_assign() so that local delivery can use the selected socket under RCU. Both address families can also prefetch a socket in UDP early demux. In both paths (BPF and UDP early demux) a reference is not guaranteed to be held on the socket. When a multicast packet is not locally deliverable, IPv6 hands the original skb to ip6_mr_input(). IPv4's ip_mr_input() similarly keeps the original skb when local delivery is not needed. Either path can put the skb on an unresolved multicast route queue or forward it after the receive-side RCU section ends. After the prefetched socket is destroyed, a later skb free invokes sock_pfree() and dereferences the stale skb->sk. Orphan the skb before each non-local multicast forwarding path. Local delivery retains the original skb; the existing skb_clone() calls provide multicast forwarding with a socket-free clone. Fixes: cf7fbe660f2d ("bpf: Add socket assign support") Fixes: 08842c43d016 ("udp: no longer touch sk->sk_refcnt in early demux") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Zhiling Zou Reported-by: Vega Signed-off-by: Zhiling Zou Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/0c52eb3d7532aaf8bccf37e0f7c922143c639735.1786552223.git.zhilinz@nebusec.ai Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/ipv4/ipmr.c | 3 +++ net/ipv6/ip6_input.c | 1 + 2 files changed, 4 insertions(+) diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index f0294b1148246..131b565c52051 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -2140,6 +2140,9 @@ int ip_mr_input(struct sk_buff *skb) if (IPCB(skb)->flags & IPSKB_FORWARDED) goto dont_forward; + if (!local) + skb_orphan(skb); + mrt = ipmr_rt_fib_lookup(net, skb); if (IS_ERR(mrt)) { kfree_skb(skb); diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c index bc535e79bdc8d..f0a98c61a087a 100644 --- a/net/ipv6/ip6_input.c +++ b/net/ipv6/ip6_input.c @@ -566,6 +566,7 @@ int ip6_mc_input(struct sk_buff *skb) if (deliver) { skb2 = skb_clone(skb, GFP_ATOMIC); } else { + skb_orphan(skb); skb2 = skb; skb = NULL; } -- 2.53.0