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 E63D85519A9 for ; Tue, 8 Sep 2026 22:54:09 +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=1788908051; cv=none; b=dcU6jUnDUDZ2kUDy+XsjITekKEl+1m70/bDGSOhS3+miKzJnzMzwN1BcuJiTAMh888iYumusQ47hx4RXL468J9jr3YQE1pKGWgJ4DF3jHcw4IVO/gL4uDp/HDpFEocMR5NfcrNfQPRzJcI9e9YAT8wvr82w0VHh82JYxUcucroM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788908051; c=relaxed/simple; bh=hBo6+MWqIJJWTzo7AILGpg46kwem+BE6XaQLlEbFz4Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XQxvX1Q/iAbnueeaw4NSxuqQ31SRpmx0cbXpuqlkHbgtfZ3OobWettozIcQl8lJg2dUMzfhMy+NWYIcykR2XdFxuXpWepQ1r1rxEHmpUUZCawmT2EbG5onSxBOqL3wmhOgNX0S90Z/ogB26FYqYMVWZaCdNwJ3y2tLK5z3t3Es0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=W577Pi2+; 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="W577Pi2+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 054FA1F00A3E; Tue, 8 Sep 2026 22:54:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788908049; bh=rC3KTR8wKNZJq4+z6fa9JU5pOc3dbu/raUjaz9bdCpo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=W577Pi2+rHQ2xX3462PEEo8jUPUDMpFScG2LbxlacO85f/HFbywYUW7PbUp+dssxf 2BTczqvGod6I9beBW/T2uayOsFbYSipSbjuldpNxCzIzr6HLptp3Xd/7yGooSowvth raQVutPnnilj5cDBk6PjmJ8IEA2SlD1Lf1pv68f1UC09DGvHqjiNjT9cXcd5CigCq5 4fp+DtMBcAM6XcUIliXKJIAO9qHbauk0VdM90KRgUCO7JSAbes3FLHmksoN1d+IVt0 TrUvVH3gYRkHhlp2LSJBDyCXFkQVxzV9PJjcsPebP0Eoe9L/3lSyDmoZSx5GHh3XJ4 v76sERu+QxXFQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Zhiling Zou , Vega , Ido Schimmel , Paolo Abeni , Sasha Levin Subject: [PATCH 5.15.y 3/3] ip: orphan prefetched skbs before multicast forwarding Date: Tue, 8 Sep 2026 18:54:06 -0400 Message-ID: <20260908225406.538697-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908225406.538697-1-sashal@kernel.org> References: <2026090319-antiques-palm-c286@gregkh> <20260908225406.538697-1-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 5e582eab1ea19..5ef20e8467e31 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -2100,6 +2100,9 @@ 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 94d2ab8689d88..403697fa5569d 100644 --- a/net/ipv6/ip6_input.c +++ b/net/ipv6/ip6_input.c @@ -555,6 +555,7 @@ 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