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 DC2A840B6D6 for ; Fri, 8 May 2026 16:44:29 +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=1778258671; cv=none; b=VYmnSjuFOziS9sg6/1VekBHOm3ld8R92/cnZGiSPzmUT4f4dvFR+Yha9luju/CYXbtVkSvCTpBtS59Z0cF1pFAaTacLS8qgFCmY6Z5wr8j7hzT7i9mE+eUEZywGYeY5QgFwRfW5FRCT/65W2JRsMSD6YzyU3AnW5I/CUmIPGh3g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778258671; c=relaxed/simple; bh=nI6jWfcws3jDGKtVHmRZ+UhUUSG86pLokLto4S1xK2Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oZoMkv1YrLB2S431T3bYe8Szv8XEH9SqkV/VmyVpSeT8St05xkl/jUF+KaSxOOJ+CjjTqt0KixjcwzPkS1srJByj/Fp6VtwQnW3gXQrKIHCpNxrEkw5pC1P3vZALdY2GxbU0K61F86SZ1osE+cDfqss8BebFw7ZvnzX3M0l9y2I= 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=eYe6ZCNN; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=feBwpVgg; 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="eYe6ZCNN"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="feBwpVgg" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1778258668; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=1SGD4ybYlVxcQvNSSgCT46FZDKdy4y6czHmnn+pucYo=; b=eYe6ZCNNuFT22h/KNO+rMSWPdqO8mqSj2wb75mPgEiN8rLkTLmsOV46R4GIiTnKWTzIQ1Z 0KqB3u7JjYLY+jZKS/Bi7ddL2opnIamzFzwB3r4nkj97jztazBq2ciEUpLbDRnPatG24RO QYYyqw7hsdSYaIW/f8UDdtdz5yH53S0= 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-256-RpJXfIAjMz2GggL2dBfp7A-1; Fri, 08 May 2026 12:44:27 -0400 X-MC-Unique: RpJXfIAjMz2GggL2dBfp7A-1 X-Mimecast-MFC-AGG-ID: RpJXfIAjMz2GggL2dBfp7A_1778258666 Received: by mail-wr1-f71.google.com with SMTP id ffacd0b85a97d-44d79da8cf7so2032920f8f.2 for ; Fri, 08 May 2026 09:44:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1778258666; x=1778863466; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=1SGD4ybYlVxcQvNSSgCT46FZDKdy4y6czHmnn+pucYo=; b=feBwpVggIs73tS2qql5DfNIny1peM0+9ekxpP6ZSXVyZdqd9Wy5tzTP2GaaNfX5yAa VJsWiOiAy4RkDB6nRH5pMLB3USg19wPYXVHTGnGFy/+VQJ/4Tqo1adg5GelUoZN5py6B lJNYexUmK+Bb+T2e0xoqZSIFJDfOd9VwnDtP0M8qjGDr4c95M59wQA0FWjx5VqiVXzsD ATveWj9F2tqZg6OTLzEKHp4G/opz+jcL6Xs5VKQXrBk5qakJFw9aPp5Qm3f0FqzFBHS9 OarpJr11spJ4lIgHigueg4qMQWvHYoZsAiggzCwNdCgkKMVSV2zngpLI2nMol+doiTLu owCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778258666; x=1778863466; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=1SGD4ybYlVxcQvNSSgCT46FZDKdy4y6czHmnn+pucYo=; b=KKA2RSWqVT4wR43seuTj501S3nBTC1I6/9fDYITvEUOceH0e+1S8DUjOWvRoFIp4dN s/lCBuStncbtpqsT6JBKKlRjsepF3U4ai0DlUJUlY5ftHuOxlrsw8R5MwLghWkwd30Vm Vu3b3dsKmo75v4xMwMoYyBEgOZK0X2GYSoyqL86U/W9fF4DfC63YEgAeK+OOX5mAvl2U rYCUnKLlm5AU0tBl8vY7+xZekqypJcf40zJszbkx0UpG0Xb+D0hfYbdVN2lKBl7K239u 5D0t1Hop3CEojvOBduvnb9Yu4ha2jNrc3s5YUprENEnZYvShCIgVFSLjv0wsB+axSDvq e8vg== X-Forwarded-Encrypted: i=1; AFNElJ/ogh9bvOCIIveoji6L9hngmPs1t2LeOeeyHrsq91NVLulDJqXOzLtWp9Ush2s+JjsmPp0=@vger.kernel.org X-Gm-Message-State: AOJu0YyW9psfQakoJEViGwpdY0kGyqvCTRgDfOLRs3DtEJatxEmnEkYk K3+e4XH65rIF+pTL79KJl8t/s8vBINXZWs7wWLhYqYnLObP+XNs1CMetqJq1iBPXRm94xbe567e Rlu2Fz2S/Im+2Lsg++h8CeWUjAZFsLMdKVwmDkBEm+7fPZCnsiXu+7w== X-Gm-Gg: Acq92OGmmbbOfj+dsDtS84ATYWHotj3v2kFC71GmKQGH5RGukiIhKBaDvaSNr8Sg/sY 9zDlPYfjwCZ8HeGCnltiMeuIv57BPPLL4E/dbetAsheLK62BrmoxdpgHX/qG7hu6wr2zhonQy8R yfgPeQ8/BiSalqlmc/bBdn/ELzfQxZ0bj4Z726KXj+Hv3Pka4KzujptyXjA8jjM7acWyuwb2CZ9 osrLk1yYNT3lAVO3pjyR2PvGN7oFPvrLPtIJpqr6QHGELSWr3egkuqOZp76MZc5txDzmUlfYipf 9FsEz4IAXt2066WNa5grAUEyMaJIkT6icbzt6QltPnc8KaYEqX/7nhtS9NRWokKcZt98WFnjeJo S4/4/6s4rmGrBFbZcWqcnESQH2iQvl5Uwweh+91AAeIbETHLnU1YWV8V4d10ZQXm4Yw== X-Received: by 2002:a5d:5d08:0:b0:44e:1984:5f3e with SMTP id ffacd0b85a97d-4515d3dc343mr20223720f8f.31.1778258665062; Fri, 08 May 2026 09:44:25 -0700 (PDT) X-Received: by 2002:a5d:5d08:0:b0:44e:1984:5f3e with SMTP id ffacd0b85a97d-4515d3dc343mr20223444f8f.31.1778258662937; Fri, 08 May 2026 09:44:22 -0700 (PDT) Received: from stex1.redhat.corp (host-87-11-6-2.retail.telecomitalia.it. [87.11.6.2]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4548e6a5b65sm5572801f8f.8.2026.05.08.09.44.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 May 2026 09:44:22 -0700 (PDT) From: Stefano Garzarella To: netdev@vger.kernel.org Cc: Yiqi Sun , Stefano Garzarella , linux-kernel@vger.kernel.org, Xuan Zhuo , "Michael S. Tsirkin" , Stefan Hajnoczi , kvm@vger.kernel.org, Simon Horman , Bobby Eshleman , Jason Wang , Jakub Kicinski , "David S. Miller" , virtualization@lists.linux.dev, Eric Dumazet , Paolo Abeni , Arseniy Krasnov , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Bobby Eshleman Subject: [PATCH net 2/2] vsock/virtio: fix empty payload in tap skb for non-linear buffers Date: Fri, 8 May 2026 18:44:11 +0200 Message-ID: <20260508164411.261440-3-sgarzare@redhat.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260508164411.261440-1-sgarzare@redhat.com> References: <20260508164411.261440-1-sgarzare@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Stefano Garzarella For non-linear skbs, virtio_transport_build_skb() goes through virtio_transport_copy_nonlinear_skb() to copy the original payload in the new skb to be delivered to the vsockmon tap device. This manually initializes an iov_iter but does not set iov_iter.count. Since the iov_iter is zero-initialized, the copy length is zero and no payload is actually copied to the monitor interface, leaving data un-initialized. Fix this by removing the linear vs non-linear split and using skb_copy_datagram_iter() with iov_iter_kvec() for all cases, as vhost-vsock already does. This handles both linear and non-linear skbs, properly initializes the iov_iter, and removes the now unused virtio_transport_copy_nonlinear_skb(). While touching this code, let's also check the return value of skb_copy_datagram_iter(), even though it's unlikely to fail. Fixes: 4b0bf10eb077 ("vsock/virtio: non-linear skb handling for tap") Reported-by: Yiqi Sun Signed-off-by: Stefano Garzarella --- net/vmw_vsock/virtio_transport_common.c | 40 ++++++++----------------- 1 file changed, 12 insertions(+), 28 deletions(-) diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index a678d5d75704..989cc252d3d3 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -136,27 +136,6 @@ static void virtio_transport_init_hdr(struct sk_buff *skb, hdr->fwd_cnt = cpu_to_le32(0); } -static void virtio_transport_copy_nonlinear_skb(const struct sk_buff *skb, - void *dst, - size_t len) -{ - struct iov_iter iov_iter = { 0 }; - struct kvec kvec; - size_t to_copy; - - kvec.iov_base = dst; - kvec.iov_len = len; - - iov_iter.iter_type = ITER_KVEC; - iov_iter.kvec = &kvec; - iov_iter.nr_segs = 1; - - to_copy = min_t(size_t, len, skb->len); - - skb_copy_datagram_iter(skb, VIRTIO_VSOCK_SKB_CB(skb)->offset, - &iov_iter, to_copy); -} - /* Packet capture */ static struct sk_buff *virtio_transport_build_skb(void *opaque) { @@ -214,13 +193,18 @@ static struct sk_buff *virtio_transport_build_skb(void *opaque) skb_put_data(skb, pkt_hdr, sizeof(*pkt_hdr)); if (payload_len) { - if (skb_is_nonlinear(pkt)) { - void *data = skb_put(skb, payload_len); - - virtio_transport_copy_nonlinear_skb(pkt, data, payload_len); - } else { - skb_put_data(skb, pkt->data + VIRTIO_VSOCK_SKB_CB(pkt)->offset, - payload_len); + struct iov_iter iov_iter; + struct kvec kvec; + void *data = skb_put(skb, payload_len); + + kvec.iov_base = data; + kvec.iov_len = payload_len; + iov_iter_kvec(&iov_iter, ITER_DEST, &kvec, 1, payload_len); + + if (skb_copy_datagram_iter(pkt, VIRTIO_VSOCK_SKB_CB(pkt)->offset, + &iov_iter, payload_len)) { + kfree_skb(skb); + return NULL; } } -- 2.54.0