From nobody Fri Nov 29 08:32:00 2024 Received: from mail-ej1-f50.google.com (mail-ej1-f50.google.com [209.85.218.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2BBCA178388 for ; Tue, 24 Sep 2024 09:01:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.50 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727168488; cv=none; b=bw/oYi5eqmkV3N1aYxdaOApqthD5hWsrcjUFciCEV9k6RK6jNQNgRtAEcyZZWSB0n7VVdkSc0Os2JjknXlVIUniCflnAuHgwov4uzqgw4XDNJikh0qxwiyVufmZ64b2ANjU9qn7+L8bCynHx9KIC7c4Qwpllbj7nPaoMUyFy5gg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727168488; c=relaxed/simple; bh=VYv+sy+VDukn69W3Bu5/T2bthOtDJXnePcCJtj3KG4w=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To; b=t+zqnuCDazxxpqRZFVbfVp2DaKl95n/algqCIfXUDnqP2OSUaTtxRss8ywBqJASwNHpiuA9g1mZ3OMjm7mAD2syYbF+6cfB5pDbLlm+8RXKFQKTAIxppiuJlzXLYP520svPsis62XjiXNIlCQLo4RKThQsXNxekA+3WXCBRZRFQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=daynix.com; spf=none smtp.mailfrom=daynix.com; dkim=pass (2048-bit key) header.d=daynix-com.20230601.gappssmtp.com header.i=@daynix-com.20230601.gappssmtp.com header.b=zupO9Ba2; arc=none smtp.client-ip=209.85.218.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=daynix.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=daynix.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=daynix-com.20230601.gappssmtp.com header.i=@daynix-com.20230601.gappssmtp.com header.b="zupO9Ba2" Received: by mail-ej1-f50.google.com with SMTP id a640c23a62f3a-a8a7b1c2f2bso878623066b.0 for ; Tue, 24 Sep 2024 02:01:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=daynix-com.20230601.gappssmtp.com; s=20230601; t=1727168485; x=1727773285; darn=vger.kernel.org; h=to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=1z2jVjMLVH28Vvu6Jrp+eHoNG85dGW4/noaq6q8us20=; b=zupO9Ba2eoaQV4vuwKtBUj2VFLr9Q98dCTZWlgvFOWpYJOo42ecmed61dm2HzIX0Wi B6+eZSOflcBWi7BcdcBTTy1VuJgKMgq87+KeVSxAIN1zaWssrfIispNgq/HqKSei82kf G3Q6vL/R7KYx+3y/EwcnPXLhbonqH1vZsLhhYtzewuEbbUkPUwajUHUCKij7evnY3eej Me8/wVdbZ5FoPxG4AEX4rVUGt/l0hlHPop8jKU9Gyho7zLfX6GF76nq6oRgzgh8BhCW6 9E9lcTPHk49j4QJFVfHqzd0Tzi/O4+/a1dcgdgEOSYKif3TvfuYo8kKkARWiHB/Psjw7 d15w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727168485; x=1727773285; h=to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=1z2jVjMLVH28Vvu6Jrp+eHoNG85dGW4/noaq6q8us20=; b=KIG5adD1FSM6e5i18O+kq3ogBKZrX94nXj5eEXsD8BRYNrmBPORzT/prSap4Sbb/Z2 VnfnQ1BjDFbN7Vwke3tNVwRIUTh09uxz8iVYbKnQGn7ZJnMscfvSXYx0P3+TAfdgRrdi /TOXm2YOCvShFTItCKZkitmWCpVVixUV6CIK4U0l0yG5e6TEualqVqA3ELnguDa7uR4f s/Ra7auyKHDYD/UC4vn3/jq+t5Q+NhDMAnDdAH8unoPfFZ+FqRIBug1umz7V6U5gRXQt 3h0xSHKVitYSJbXpLf9QzQFvCE5Wm2nK8ACCy8hhlZEq1mt2kuCta1sH5348nNmONXd5 UTVw== X-Forwarded-Encrypted: i=1; AJvYcCVMraQK9FwtXytXgjH3ql/sh5CGEBBNMuEEFyZEx6jWJm4NsASCRQLDSfFe/GV6NqhqBg5slgHZYHjbm8w=@vger.kernel.org X-Gm-Message-State: AOJu0YyT4E7nFLYRhA76t3XEYaQhLAaRp2ZUq2RYevITwdBVbOWWkRrH IzL7eE5uQRMQVRZsotvuX2ymt41d5IXX72fcucuE3A/VwKAf6NV7SAwTYCkjgWI= X-Google-Smtp-Source: AGHT+IHUq/dkWRpPMqsa4EeYb9S0z67V0A8NcjQ83e5aXy7PtfQ3vrN7fPuwMQhOhYz1y6x1alrMzg== X-Received: by 2002:a17:907:e212:b0:a90:430e:6a34 with SMTP id a640c23a62f3a-a90d503382dmr1557301366b.31.1727168485178; Tue, 24 Sep 2024 02:01:25 -0700 (PDT) Received: from localhost ([193.32.29.227]) by smtp.gmail.com with UTF8SMTPSA id a640c23a62f3a-a9393138be1sm58586966b.219.2024.09.24.02.01.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Sep 2024 02:01:24 -0700 (PDT) From: Akihiko Odaki Date: Tue, 24 Sep 2024 11:01:10 +0200 Subject: [PATCH RFC v4 5/9] tun: Pad virtio header with zero Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20240924-rss-v4-5-84e932ec0e6c@daynix.com> References: <20240924-rss-v4-0-84e932ec0e6c@daynix.com> In-Reply-To: <20240924-rss-v4-0-84e932ec0e6c@daynix.com> To: Jonathan Corbet , Willem de Bruijn , Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "Michael S. Tsirkin" , Xuan Zhuo , Shuah Khan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kselftest@vger.kernel.org, Yuri Benditovich , Andrew Melnychenko , Stephen Hemminger , gur.stavi@huawei.com, Akihiko Odaki X-Mailer: b4 0.14-dev-fd6e3 tun used to simply advance iov_iter when it needs to pad virtio header, which leaves the garbage in the buffer as is. This is especially problematic when tun starts to allow enabling the hash reporting feature; even if the feature is enabled, the packet may lack a hash value and may contain a hole in the virtio header because the packet arrived before the feature gets enabled or does not contain the header fields to be hashed. If the hole is not filled with zero, it is impossible to tell if the packet lacks a hash value. In theory, a user of tun can fill the buffer with zero before calling read() to avoid such a problem, but leaving the garbage in the buffer is awkward anyway so fill the buffer in tun. Signed-off-by: Akihiko Odaki --- drivers/net/tun.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 1d06c560c5e6..9d93ab9ee58f 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -2073,7 +2073,7 @@ static ssize_t tun_put_user_xdp(struct tun_struct *tu= n, if (unlikely(copy_to_iter(&gso, sizeof(gso), iter) !=3D sizeof(gso))) return -EFAULT; - iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso)); + iov_iter_zero(vnet_hdr_sz - sizeof(gso), iter); } =20 ret =3D copy_to_iter(xdp_frame->data, size, iter) + vnet_hdr_sz; @@ -2146,7 +2146,7 @@ static ssize_t tun_put_user(struct tun_struct *tun, if (copy_to_iter(&gso, sizeof(gso), iter) !=3D sizeof(gso)) return -EFAULT; =20 - iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso)); + iov_iter_zero(vnet_hdr_sz - sizeof(gso), iter); } =20 if (vlan_hlen) { --=20 2.46.0