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 3A6D844AB7B; Tue, 21 Jul 2026 22:09:35 +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=1784671776; cv=none; b=MkSbC8aG1t3a6fT9NN5Zy//24IFUJZpetbvE2lIEuIOCEcXVlm7Hj+GxInKd/7XaK87+HP2r6dBpQmszCx/gVYeLV61BHaun8xOfSovnAX44EQhltW3K2XiZ1jeHUTseVqlePHl3+zlooLuT8f2NHSRYUOnxKQlY8RlZRScZ/3Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784671776; c=relaxed/simple; bh=R0JVo3ptWqWWh4btrU/WgF+vb2KnUVrsyGSfZjj9CNA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=C9NYvoDe0+VHfu0xqDdo7QcyRG6hFSCYNi8ShSsAC9rCa/reBQo5YTzFbM2t6XdEKrjDnGwPUbMMKmBsJjhfl9kQmy594FoeSRtQgp/zfwvUrqLG1J6QGiDLm05YhTllST75lZMNTu4ZZNq76o2T8b03CHxQYIcerjWYvx4pnWw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=G29x0SEN; 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="G29x0SEN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A43E11F000E9; Tue, 21 Jul 2026 22:09:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784671775; bh=L687iuPQjmWb38Em/8bZHDJpE9yfu9kRXcPE5OcViJg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=G29x0SENBe1Msp2Ej/sT40eoggyr6RkDoQ3gjVS8VGvsXyCcS72c2qfeB+t1TaOI5 cVar+Z4pJ5v1WOnfDTDrHGmivsX6PgaIQAP0VYNK+qy8hjN+GpGVmtrh3lIEouSNc4 OEAlwba8qRGMM5wLNx/rZZSC/qOmyCqY5NrWX6IA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jiayuan Chen , Jakub Kicinski , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Sun Jian , Alexei Starovoitov , Sasha Levin Subject: [PATCH 5.15 357/843] bpf: Run generic devmap egress prog on private skb Date: Tue, 21 Jul 2026 17:19:52 +0200 Message-ID: <20260721152414.064065370@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sun Jian [ Upstream commit 6001896f00984d317fb75160ba05c4a885fbe2a0 ] Generic XDP devmap multi redirect uses skb_clone() for intermediate destinations and sends the last destination with the original skb. This can leave multiple destinations sharing the same packet data. This becomes visible after generic devmap egress-program support was added: a devmap egress program may mutate packet data, and another destination sharing the same data can observe that mutation. Native XDP broadcast redirect does not have this issue because xdpf_clone() copies the frame data for each destination. Generic XDP should provide the same per-destination isolation before running a devmap egress program. Fix this by making cloned skbs private before running the generic devmap egress program. Use skb_copy() instead of skb_unshare() so allocation failure does not consume the skb and the existing caller error paths keep their ownership semantics. Fixes: 2ea5eabaf04a ("bpf: devmap: Implement devmap prog execution for generic XDP") Suggested-by: Jiayuan Chen Suggested-by: Jakub Kicinski Reviewed-by: Toke Høiland-Jørgensen Signed-off-by: Sun Jian Link: https://lore.kernel.org/r/20260612114032.244616-2-sun.jian.kdev@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/devmap.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 6ad4b068abc770..0e67e6cabdb689 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -676,6 +676,18 @@ int dev_map_generic_redirect(struct bpf_dtab_netdev *dst, struct sk_buff *skb, if (unlikely(err)) return err; + if (dst->xdp_prog && skb_cloned(skb)) { + struct sk_buff *nskb; + + nskb = skb_copy(skb, GFP_ATOMIC); + if (!nskb) + return -ENOMEM; + + nskb->mac_len = skb->mac_len; + consume_skb(skb); + skb = nskb; + } + /* Redirect has already succeeded semantically at this point, so we just * return 0 even if packet is dropped. Helper below takes care of * freeing skb. -- 2.53.0