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([2a0d:3344:271f:bc10:144e:d87a:be22:d005]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b5e8dc1ecbsm1422399f8f.25.2025.07.10.02.57.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 10 Jul 2025 02:57:51 -0700 (PDT) Message-ID: Date: Thu, 10 Jul 2025 11:57:50 +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 v2] virtio-net: fix received length check in big packets To: Bui Quang Minh , 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 , Gavin Li , Gavi Teitz , Parav Pandit , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org References: <20250708144206.95091-1-minhquangbui99@gmail.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250708144206.95091-1-minhquangbui99@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/8/25 4:42 PM, Bui Quang Minh wrote: > 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. > > 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); Minor nit (not intended to block this patch): since you are touching this, you could consider replacing the BUG_ON() with a: if (WARN_ON_ONCE()) . /P