From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 91EDD38331C for ; Tue, 1 Sep 2026 10:10:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788257448; cv=none; b=n+3Ni1EAmcEEvowUmiHE45J6NIFDgkI9+gvjsFrbAbNIy79+E8lYS/F73FYmudGpHy8dyH/Tpqbo2IrIxwEsmWtx0Ft2V0ySU2ZgAiDsIV2zxO+OMddhEdg4vLMUR50SclZxptbAHgo0bB0yMbJ07VIkcu1T/319UJ451K3E+70= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788257448; c=relaxed/simple; bh=eCiXJ0V1lD61eU/nkm8ptcqiGA2d3BIel3Y3IprKT38=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YVpBXlrIndUzckMvK00RJh/lYIRsboPKfSIAcfDoid96066YtK9ShsH6aEgpHJ7xhjbWRqOwp2JHvYorwcMrbKnxWWnaWvow+yhHVpnK02QmFfjKLztpquCu+1TOu8BZeIfoGGR83eiI7sXOcg+Qk5Okjz6am41YlkblRtUQqgQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=JMdoaF1+; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=LhGDhSlr; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JMdoaF1+"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="LhGDhSlr" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1788257445; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ACL54tT4vMHsYH0XEuJ1PQI1LaYJnFwQ29QPKJ7kRX8=; b=JMdoaF1+SDQFe5BbwSNgWXlTrSFwT6RVKPXobm7xDF/pIhXiPMnGo3TLTw2p+x+Ec3CTkT kcZewsDrw6RpPQcaecQ4gUoIW3d7TeKLlP07TpQ4leU0rqrbmPYLTSaPk0IVay7iHPEi3c xz7VkWO5pST/8Zc1J7AmOE+9TfLkTJw= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-272-iXjp41XpOLGmSmma7Hr-Dw-1; Tue, 01 Sept 2026 06:10:36 -0400 X-MC-Unique: iXjp41XpOLGmSmma7Hr-Dw-1 X-Mimecast-MFC-AGG-ID: iXjp41XpOLGmSmma7Hr-Dw_1788257436 Received: by mail-wr1-f71.google.com with SMTP id ffacd0b85a97d-484337a63bbso1898402f8f.3 for ; Tue, 01 Sep 2026 03:10:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1788257436; x=1788862236; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to:content-type; bh=ACL54tT4vMHsYH0XEuJ1PQI1LaYJnFwQ29QPKJ7kRX8=; b=LhGDhSlrf+Er51VzBuOG21/scn3624sohXDDOfFUiVa1/0/4nCly9+hpSbS+WOfmTK TKZOxm7qClycm9NoirhmWjNlLVMJ0Ps/2B5jJEJ5rq6gnQij3xpc91ac8QbUPx19kRxZ 2YFk4JtVrls6lZohSiioJoSkbDwX1JD2xzbE5tJFdr86LMIsIX1lFLlOu94QcIx7Qf/0 FG86KvmykgXdt9q6xsKSp4VEwYdQKJUIhL5RiCSJrC1PzRggapc3D/WYtPpX8mOwckbr Ks/lxVC9A0410iZQaLbcUJZXRggbPMlp1A9K7tYB2H7xEHwtXI65OD7LTyOOMlQGgZVS f9Ug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788257436; x=1788862236; h=content-transfer-encoding:content-type:in-reply-to:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=ACL54tT4vMHsYH0XEuJ1PQI1LaYJnFwQ29QPKJ7kRX8=; b=rNTAClsMlBu7qJJhxPgljYUiodPc1JgK2zrJC2weUuhU/byTUZSTcRT6PSbydrp04B uWaZtf8X+wKSQs8hZ+yEZBtVWPVB7bUtxp2DCLSSaArDIqWADb+M1KnKJBR4bIWxo14w vBJ3G7SIQH6kiUe9TvZq238IKICSEGbIfrvzCKiJDZR5HQYZ+N4SIy3vmKJ4BjSsbuyp n5SDiaEVdlRlPzWFzm6qDfMU0qtr63rSB0gH7eEN8rTgOGtHXiodBeWYO95XT+6hMQaW 8DqYV6i+0SGIoZuTyIsax9bzHd9TdBC9nH0KHOCE9XnQpiArnqK87zVY93ulkjd8rE5h yWXg== X-Forwarded-Encrypted: i=1; AKwUvByWE/GpWBaxOgZAiN2HSQer/QP/0wllHku9EKsq0rEx/ebWmbEjLyaKRCPcLtYVo6kU6RMSXE4=@vger.kernel.org X-Gm-Message-State: AFuF++lFZFwMvlssz2RqvWCQp7ec1s6EyngsBjz5NJVZ+qhzjnf3BZVB uTy/OPyWK6iIIHMkpmRzmqTtmPP2YSGxrCPE3/l544hJKfx0h50a0A/7D18jjops5dF0KQ6b81B pixRpkZsGHfcOrijzLKMavwA7HoPz8/6hVk+WM5EtRjd2QwUsx/12m8FAkQ== X-Gm-Gg: AYBFou2gsmj6GOnok/qawGUi6uQG6AJRjP4cgOT/aixibyA9vmLY16BobtZSL7UjMbI yoGWPuUpQP+Z1C1UV5+DSHMWCVa4mqRwUaOQlvv884doKvCr+0l50TjmrOstA6hDc8k9SjykVLk MZGmnSAuaNm4slL7mIcX6t7AI8RvmhJ6C8I+iQV5HCsAaTgaa+ZmbQtMI9MfCYwTRbNiJlaMejB elXl6RLBQZ4JkloKzQ2EdnSSAmFrf374nodr3m7NFJNRz/jE2A+6g1l5pVP1w61PVXJxkEpx+P2 Q6MhIdLKdTYn7C2cwnWOOHse65V9Y2cZSwVKteHVCzm1vyNq7c91tMX9s/jC97+4vCda+MgQuyk YyO6luQ62mf73xnJapohoFSH8lrQyfIA+KtF/gzXT5Kj3HSDy/G5RIgtKkBISxcAxwJLhQ/8Hkg == X-Received: by 2002:adf:f105:0:b0:481:51b7:290b with SMTP id ffacd0b85a97d-484416aadccmr9393885f8f.14.1788257435717; Tue, 01 Sep 2026 03:10:35 -0700 (PDT) X-Received: by 2002:adf:f105:0:b0:481:51b7:290b with SMTP id ffacd0b85a97d-484416aadccmr9393781f8f.14.1788257435275; Tue, 01 Sep 2026 03:10:35 -0700 (PDT) Received: from [192.168.188.218] (ip245-45-231-195.pool-bba.aruba.it. [195.231.45.245]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48442d3c4absm3951169f8f.10.2026.09.01.03.10.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 01 Sep 2026 03:10:33 -0700 (PDT) Message-ID: <53a67f9a-b8a0-4967-b2c6-be4ee3a09735@redhat.com> Date: Tue, 1 Sep 2026 12:10:32 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] vxlan: use one headroom snapshot for neighbour replies To: Sanghyun Park , netdev@vger.kernel.org Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , David Stevens , linux-kernel@vger.kernel.org References: <20260831054614.2069896-2-sanghyun.park.cnu@gmail.com> From: Paolo Abeni Content-Language: en-US In-Reply-To: <20260831054614.2069896-2-sanghyun.park.cnu@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/31/26 7:46 AM, Sanghyun Park wrote: > vxlan_na_create() samples LL_RESERVED_SPACE() to size the reply skb and then > samples it again to reserve headroom. A concurrent vxlan_changelink() can > update needed_headroom between the two reads, creating a TOCTOU race. The > second value can exceed the allocation and make the Ethernet header write out > of bounds. > > Snapshot the headroom once and use that value for both allocation and > reservation. > > Fixes: 4b29dba9c085 ("vxlan: fix nonfunctional neigh_reduce()") > Signed-off-by: Sanghyun Park The patch LGTM, but the changelog needs some improvements: if you have can observe a splat on the unpatched kernel, please include it, otherwise please explain whythe issue is not just a theoretical one. Also please specify if some LLM has been used. Thanks, Paolo