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 8D343566C6D for ; Tue, 8 Sep 2026 22:37:09 +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=1788907032; cv=none; b=e0bbJPnEdMmzC2zBUcmRXppZzBDxYHjwDFU3PfifwiHv9h/hYFG9O5nJteZAmlv0zwddObC+KKX6OuQN4Bc3YqUtCp962ik/3YfZGijD1BK8cYBjnsM4bKGfXGa/kgSfSbeJ6wremFuXO21BGcwe8AT1LvnRYDyHEFUjwTci6zY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788907032; c=relaxed/simple; bh=TpCiLhw4fC965Rb3IT12gy4z9e3Cbz/BZL2bV+6BlL8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hBNimUnZnKw9KCrOCssdpaiNGOyuvdUS4fDfmxWoB70yDRXs6y8lVq9IKYzOnLbhVa97zT/a2PnYL3httiiXuCL5B71ineztXP2p7h7N2k4+OvLwmQe/nNz8jRobQNEhsfUr0tEwLNq0wPpaiZZZdpU0HIg/YE1ERJEDs9zV79Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hLlxlaSg; 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="hLlxlaSg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 675091F00A3F; Tue, 8 Sep 2026 22:37:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788907029; bh=sKXNR+TbjXzGNdPDoWypRRG88bh3bxFz56y9jzrYimo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hLlxlaSgduWOvALvHk7nv5NJ/8J4WTE9B4zb9z++A4FGLUJlzYKWXJBVHtyrxQJ/Q 2w3MIqU9u6Es5sDQ+qX2DPX5KAAoUMNuiSVOaOCmIy1OOKiBFRY3owhpIOoJJjlJos YFmF5MtzJuT/P5OgWYjTWQnqICEwLSep2wtDminFnhyOBqfZSn8UBMkMVzCE1Sl4mJ T1SKp5fluTSYFEq9OnN0aO6LXa3DyYMh/4gRwVUhozPEOu/+0IeqF8vmGIN1TKxEHm UHQ/xkTf87kAKbYyfCoxE385LykPxNEoT1H6iS+e8Aim9B/qAMwHIiePgbDWqkyeaB /U3M8oDhl/EMQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Zhiling Zou , Vega , Ido Schimmel , Paolo Abeni , Sasha Levin Subject: [PATCH 6.1.y 3/3] ip: orphan prefetched skbs before multicast forwarding Date: Tue, 8 Sep 2026 18:37:05 -0400 Message-ID: <20260908223705.504692-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908223705.504692-1-sashal@kernel.org> References: <2026090319-football-expel-7883@gregkh> <20260908223705.504692-1-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 f64651c0dea6c..948f6faf1d04f 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -2125,6 +2125,9 @@ 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 a341427a5fa43..614998b5af2d4 100644 --- a/net/ipv6/ip6_input.c +++ b/net/ipv6/ip6_input.c @@ -572,6 +572,7 @@ 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