From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f171.google.com (mail-pf1-f171.google.com [209.85.210.171]) (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 0B89F23BCEE for ; Mon, 27 Oct 2025 14:37:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761575856; cv=none; b=SJuQNGkszX7drwoQ6yCJPa+j7qt4Av8R4lAtlXEPo8EI3ft4p+EDB4f9TOGocf8r0iZpcK6ueukYVefXsHFFKSUJE0/SkvtnybdEcTA11nr1YSEY6gekpAZHdF1QG1VYKkSzLG7+PGqemShDB+ZRsdtKESAk5CsLr3Qm+4InF9k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761575856; c=relaxed/simple; bh=adn7NhSXM4F+uMTSsRmO9V9GvUSLky72zBSuV3U4ELM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=e4Af9x7i9odJ4ZGpiJ4ExlreLhngBRPBjVXb2EcnQ+kzJlRSF3SnrHOpo/UrHxLo9ahtm9VklkhuhVRyNPzaM/mNQrZuPUwM9PVanpl3zcJF62FZSMyBuxwVZbUg4Wp98OI+0jhB2/F6Ey+os0eLB3sxWUVF3RLm69yrA3zb0OE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=e0bSv9LS; arc=none smtp.client-ip=209.85.210.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="e0bSv9LS" Received: by mail-pf1-f171.google.com with SMTP id d2e1a72fcca58-7a27bf4fbcbso3877177b3a.1 for ; Mon, 27 Oct 2025 07:37:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1761575854; x=1762180654; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=4B2eLu4llGXCU4gdWSthJqBowpW96zatbh6aox0b+bY=; b=e0bSv9LSMLGnUeVspq1SLeSkr751kmjCy2clTjBW7kOYOko7npqJfCEHVKqhoJ2N3n znpD9EBNgOSTUzCNmcEJ5vf74Oi6sqshROnLL9bRoPDzeQplihCKvUX2KbmVyPzLY4MR 7fMdsZn3oPCvWQhJDlNJZhSx583KCFrH9yBlio/8FE1OT1s+B6BDMB18VUy1/B8c49b2 UgST7igncY1DlvPoKPrX6YUZ4oRq19MUkrasDH3LodHdRbCyx1FjmG3YYxaJaoKNX+LQ dRFp8sky/Tn7VgowolRlhGeR+K7AHlVLp96s/R88rt2lcL5AnUHm1M+z1ascOi+ZMaK1 13yQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761575854; x=1762180654; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=4B2eLu4llGXCU4gdWSthJqBowpW96zatbh6aox0b+bY=; b=YI7lzWlKG4MYkNn+Ci+t4JodQ1L3kNfo1Kiu79+YR+pVsHXfF7Gmko4DxbaNSDlhKc NCNMVDf7H66MZMdntGnHcGjPigIjP3QiAzjFdvrmfiRtRV2ZJTOvlQWK1uNq0eK7vlst dSTjHn6/H/NxwM9i49PalgU0GNw1zJUxTZxC7hLDniPZlkQr45mOprUQSef5etPFlgP8 cCoNHOKHpVcf8dhgw/z0cV9Fh1XCrx4S0IhySxSKRhauVOLWUNejOkpo8/Boszt2Ps5+ oGuUQ67hQX999+yCrEAVfiAFo8EQkczCbtuL7+2MjuKsZpgYKpbznBVz20CO3mAEyfzl +2cg== X-Forwarded-Encrypted: i=1; AJvYcCUc/vdaTZW4Dc6RvWaNmQP2OBn/+Ng8mxZVlAwxlTh/johIWbXJQWyaNg3b/mtDM/TN3Rx4WJHhb0gIOX4=@vger.kernel.org X-Gm-Message-State: AOJu0Yycr1snJdRgXdm1K3BOheQZMHPfYdo8VTsWBvwWkP0FecLv6UYL r5+pjqODt9daf6mk642FA41jtDy0NXBYb+IrTYIcaFr58KED+ukX7Tp4 X-Gm-Gg: ASbGncud3auTo2evLEktFPGAUzBAEv7aB6yTMQbN3fhptCAHX+nn/ohrimTvVpYe7fE yyjf5VZo5Q8AcgAYjo+fgpGWqv26csxAgYFAqAb9jklolmbCxYjVrI6ic4uVR0jUzPll8AKVOZq 1HaPsC0cfDhh55l2X4xiIWtJk0BmkLvkVxCT65syA4qXjm9B2JCjXkRyQ9xKmQg1qYJANKzg0Pg s9jZ6nyKNTjmhjTRnp8jKRVSOji6PkBzH78m06fn/v++vlSZQtWOpZPaWcsydna0YnPFMZby9RA 1q5j3yMgnGuvpp23jJFni5c0edU6ecDYeSyuYnZR6cOtIagk0n4nHthuULyO5F3fs0vBZRKkkHg 531Q5yqHLGwR/378LqZIjpaohVfIx+biCfE58TsONTdZNAgMMQVY4afgU12eNI2D7Or3IiGEFyH 2QDt6GA+8IZJTIxE0ns9mLAGYsq67nrgsIHLR89c4qprgVtv1+31bo67ygPwBs/07DuXISIGKZ X-Google-Smtp-Source: AGHT+IGTA/k5UQ2FNEr9mRS1Wz3fIDbx1lAqcpQR27aZ9cZE/UvwNhDm/mbd//iNK1nFji1/GqjjHQ== X-Received: by 2002:a05:6a20:72a3:b0:334:79cd:fb13 with SMTP id adf61e73a8af0-334a85047abmr48082035637.4.1761575853948; Mon, 27 Oct 2025 07:37:33 -0700 (PDT) Received: from ?IPV6:2001:ee0:4f4c:210:d7dc:fc1f:94d0:3318? ([2001:ee0:4f4c:210:d7dc:fc1f:94d0:3318]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7a414087cdbsm8438806b3a.64.2025.10.27.07.37.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Oct 2025 07:37:33 -0700 (PDT) Message-ID: Date: Mon, 27 Oct 2025 21:37:24 +0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v5] virtio-net: fix received length check in big packets To: Xuan Zhuo Cc: "Michael S. Tsirkin" , Jason Wang , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Gavin Li , Gavi Teitz , Parav Pandit , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, netdev@vger.kernel.org References: <20251024150649.22906-1-minhquangbui99@gmail.com> <1761527437.6478114-1-xuanzhuo@linux.alibaba.com> Content-Language: en-US From: Bui Quang Minh In-Reply-To: <1761527437.6478114-1-xuanzhuo@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/27/25 08:10, Xuan Zhuo wrote: > On Fri, 24 Oct 2025 22:06:49 +0700, Bui Quang Minh wrote: >> Since commit 4959aebba8c0 ("virtio-net: use mtu size as buffer length >> for big packets"), when guest gso is off, the allocated size for big >> packets is not MAX_SKB_FRAGS * PAGE_SIZE anymore but depends on >> negotiated MTU. The number of allocated frags for big packets is stored >> in vi->big_packets_num_skbfrags. >> >> Because the host announced buffer length can be malicious (e.g. the host >> vhost_net driver's get_rx_bufs is modified to announce incorrect >> length), we need a check in virtio_net receive path. Currently, the >> check is not adapted to the new change which can lead to NULL page >> pointer dereference in the below while loop when receiving length that >> is larger than the allocated one. >> >> This commit fixes the received length check corresponding to the new >> change. >> >> Fixes: 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big packets") >> Cc: stable@vger.kernel.org >> Signed-off-by: Bui Quang Minh >> --- >> Changes in v5: >> - Move the length check to receive_big >> - Link to v4: https://lore.kernel.org/netdev/20251022160623.51191-1-minhquangbui99@gmail.com/ >> Changes in v4: >> - Remove unrelated changes, add more comments >> - Link to v3: https://lore.kernel.org/netdev/20251021154534.53045-1-minhquangbui99@gmail.com/ >> Changes in v3: >> - Convert BUG_ON to WARN_ON_ONCE >> - Link to v2: https://lore.kernel.org/netdev/20250708144206.95091-1-minhquangbui99@gmail.com/ >> Changes in v2: >> - Remove incorrect give_pages call >> - Link to v1: https://lore.kernel.org/netdev/20250706141150.25344-1-minhquangbui99@gmail.com/ >> --- >> drivers/net/virtio_net.c | 25 ++++++++++++------------- >> 1 file changed, 12 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >> index a757cbcab87f..2c3f544add5e 100644 >> --- a/drivers/net/virtio_net.c >> +++ b/drivers/net/virtio_net.c >> @@ -910,17 +910,6 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, >> goto ok; >> } >> >> - /* >> - * Verify that we can indeed put this data into a skb. >> - * This is here to handle cases when the device erroneously >> - * tries to receive more than is possible. This is usually >> - * the case of a broken device. >> - */ >> - if (unlikely(len > MAX_SKB_FRAGS * PAGE_SIZE)) { >> - net_dbg_ratelimited("%s: too much data\n", skb->dev->name); >> - dev_kfree_skb(skb); >> - return NULL; >> - } >> BUG_ON(offset >= PAGE_SIZE); >> while (len) { >> unsigned int frag_size = min((unsigned)PAGE_SIZE - offset, len); >> @@ -2107,9 +2096,19 @@ static struct sk_buff *receive_big(struct net_device *dev, >> struct virtnet_rq_stats *stats) >> { >> struct page *page = buf; >> - struct sk_buff *skb = >> - page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, 0); >> + struct sk_buff *skb; >> + >> + /* Make sure that len does not exceed the allocated size in >> + * add_recvbuf_big. >> + */ >> + if (unlikely(len > vi->big_packets_num_skbfrags * PAGE_SIZE)) { > > I think should be: > > if (unlikely(len > (vi->big_packets_num_skbfrags + 1) * PAGE_SIZE)) { > > Thanks Sorry, my mistake. I'll fix it. Thanks, Quang Minh. > > >> + pr_debug("%s: rx error: len %u exceeds allocate size %lu\n", >> + dev->name, len, >> + vi->big_packets_num_skbfrags * PAGE_SIZE); >> + goto err; >> + } >> >> + skb = page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, 0); >> u64_stats_add(&stats->bytes, len - vi->hdr_len); >> if (unlikely(!skb)) >> goto err; >> -- >> 2.43.0 >>