From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) (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 DDA8E20B80D for ; Tue, 8 Jul 2025 14:58:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751986714; cv=none; b=pAQVy5dHHDT+OLUoGMUaQ9F/GuM5+CivJdfhIec/hp/e1By63Git0A67PETWTVfKKA7t5S5mS1vjZfqdh0nTyWeYkhUoUzPvPomwGaSIupf0fEmv8i8HLq8S5JMmhmIsUxccNQPg/vr6JDwXjXPA3K5hBQ507QcbgUOxYX2Wpms= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751986714; c=relaxed/simple; bh=+NqjU4uQXlMtOkNUF+YqZyMgp92MuypF4BvPFXX8Ve0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NxucAh/6T6Yvd/3DU+eOrWREqqmVrWv18dEwKKwG37nMOipSkiWv15wtCqVdhJz8faH3PmVyYC9MSSfoEOF+QIMny8hHtjoz6utq52JefeZO0E//LeMICXInxSfIjY8OXp1x9P6qIqgyGQz67UyaSBotSj3wBGjNPh/diLBOt9o= 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=Ohsq2SUe; arc=none smtp.client-ip=209.85.214.174 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="Ohsq2SUe" Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-23508d30142so54411735ad.0 for ; Tue, 08 Jul 2025 07:58:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1751986712; x=1752591512; darn=lists.linux.dev; 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=UWScCBjnLf2R/TIfIIUf9QArMhSADm4WDSoogHlveqE=; b=Ohsq2SUeHPYt13fAs0t5Z6NwtVNNqxcey2ITuPR4605Wue+UeIt/69omPvgVpuAo/A c3LKKPMvZIzqp10OlIW/OmZmrS4B4geETHLf8UoJa2ygIkA/nG0PPsQyXUMNgUT+4zuO JAoRzDlLDlOdZtVyX3ZJQtsHVk7YtFP0tCoBNddmRe/0fKqzE6v38EUzIXPTRULcj7JJ YhwBVBX1sWz6Hp6gYZ9FPEt8NJ9DI5KEtQldtEUcSF21OaXfJZgLqeqxYhj50eo/CJHJ EwXrktARyepVz+071t2+nBl3kfiZ/gH5YCpQ+HToBSLkhAERxg0axJ2HIxDRIinyc4r/ LNcw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751986712; x=1752591512; 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=UWScCBjnLf2R/TIfIIUf9QArMhSADm4WDSoogHlveqE=; b=PzPFgItrPAw1ZV9lnDOwbQmDb79SzyL653GQe4qc0zOgkV5xQtEeQPmCnjWcjnT35P 6+h0zpwpO112L/7jNNLM8VPmrt5sn0d5hTuvB1eIEyDqNoKY28+Jpl9bISBU7AN1VkeN UDsYScdEFvytByNqpMpzuWNq/evRBJgDcSG/b5IZY2+3aVLZCE7NXNeA+GmA3GtO0UWe kRfDwJ2Kb9vUU/ApQoz0ayPTPP5+pSDyt9/5c9cQyf8Q04SkDnOEXp2/HUhyinKgLi40 DnERdhySbyenk9j1ey6YwM18umn80LWX/kI5LQxcX1FEA1pRrv8k/5NVyc2Tuu2ZIhhS cZLA== X-Forwarded-Encrypted: i=1; AJvYcCUYAHNjY1xvr+3m1R8EcHaj8eo5cCWmJHrnV+V3smdi7cORC8xgvuk7VC3c1TISV2vUAFCwEhbcC/DF3BhFfA==@lists.linux.dev X-Gm-Message-State: AOJu0YwTwJdzRqJO4l7aewzjURuS1nNN3cwIK7YN81kREmSZzsyLWuiL 7MM5TY7yvrannkrdg5vyzY0rJESFhAilXOKuUmuTiFc6udR5RTIN1TQ8 X-Gm-Gg: ASbGncvBEyXvmouId+dYdQ5HFgzXhM2jEWztzT72xXjY0Xpb5cVu6wX5lVCUoDh5pVw vl2GfYwLWnhproUMaPwVcTtXElrgAmfXPSB40FehWSrwwVUSdI2H6gxnKP3tWgBa8TwnrPDJ0FR ozRUhs6m0Bb/D+aZtwnoONRqWWa8XipPN71wc9eASTLwcueinA+qSbwk2KnHjNgV0tdWwckW1/f ZAMB53fO3jUVWyTNuXaOzqutF2ISj3YSoKyTNQ+d08pIkkhRGZ2z8bRuT0hcRk2InZS0gIErnTP 2E0drOJD5SzvnV1RZVbkMHw/CDjXbLWJNjwwQkUpsn/aacaMZROpGCbJXTv2z1RSxKxnbqRCPDW 9zsIllRISfCwpFl/Jx0nbT93ozJLyjptJzfWE3pFE X-Google-Smtp-Source: AGHT+IGsiWMFIFsAbr8aNOe79of4TnBXH6qxow/kWKTKfQRaWTwycD8M4/HGPfM50XdIS7N54Zneag== X-Received: by 2002:a17:903:40d1:b0:235:ca87:37ae with SMTP id d9443c01a7336-23c85eb057dmr299625885ad.41.1751986712178; Tue, 08 Jul 2025 07:58:32 -0700 (PDT) Received: from ?IPV6:2001:ee0:4f0e:fb30:37c0:6356:b7b4:119a? ([2001:ee0:4f0e:fb30:37c0:6356:b7b4:119a]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23c8455d153sm115207925ad.94.2025.07.08.07.58.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Jul 2025 07:58:31 -0700 (PDT) Message-ID: Date: Tue, 8 Jul 2025 21:58:24 +0700 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v2] virtio-net: fix received length check in big packets To: Parav Pandit , "netdev@vger.kernel.org" Cc: "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "Minggang(Gavin) Li" , Gavi Teitz , "virtualization@lists.linux.dev" , "linux-kernel@vger.kernel.org" References: <20250708144206.95091-1-minhquangbui99@gmail.com> Content-Language: en-US From: Bui Quang Minh In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/8/25 21:52, Parav Pandit wrote: >> From: Bui Quang Minh >> Sent: 08 July 2025 08:12 PM >> >> Since commit 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big >> packets"), 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. This commit fixes the received length >> check corresponding to that change. The current incorrect check can lead to >> NULL page pointer dereference in the below while loop when erroneous >> length is received. > Do you mean a device has copied X bytes in receive buffer but device reports X+Y bytes in the ring? Yes, that's what I mean. AFAIK, it's not checked in the ring level. Thanks, Quang Minh. > >> Fixes: 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big >> packets") >> Signed-off-by: Bui Quang Minh >> --- >> Changes in v2: >> - Remove incorrect give_pages call >> --- >> drivers/net/virtio_net.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index >> 5d674eb9a0f2..3a7f435c95ae 100644 >> --- a/drivers/net/virtio_net.c >> +++ b/drivers/net/virtio_net.c >> @@ -823,7 +823,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info >> *vi, { >> struct sk_buff *skb; >> struct virtio_net_common_hdr *hdr; >> - unsigned int copy, hdr_len, hdr_padded_len; >> + unsigned int copy, hdr_len, hdr_padded_len, max_remaining_len; >> struct page *page_to_free = NULL; >> int tailroom, shinfo_size; >> char *p, *hdr_p, *buf; >> @@ -887,12 +887,15 @@ static struct sk_buff *page_to_skb(struct >> virtnet_info *vi, >> * tries to receive more than is possible. This is usually >> * the case of a broken device. >> */ >> - if (unlikely(len > MAX_SKB_FRAGS * PAGE_SIZE)) { >> + BUG_ON(offset >= PAGE_SIZE); >> + max_remaining_len = (unsigned int)PAGE_SIZE - offset; >> + max_remaining_len += vi->big_packets_num_skbfrags * PAGE_SIZE; >> + if (unlikely(len > max_remaining_len)) { >> 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); >> skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page, offset, >> -- >> 2.43.0