Re: [dpdk-dev] [PATCH v3] net/bonding: fix potential out of bounds read

[Chas Williams <3chas3@gmail.com>]

On 4/18/19 2:41 PM, Ferruh Yigit wrote:
> On 4/17/2019 3:36 PM, Radu Nicolau wrote:
>> Add validation to pointer constructed from the IPv4 header length
>> in order to prevent malformed packets from generating a potential
>> out of bounds memory read.
>>
>> Fixes: 09150784a776 ("net/bonding: burst mode hash calculation")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Radu Nicolau <radu.nicolau@intel.com>
> 
> Hi Chas,
> 
> Do you have any objection on the patch?
> Functionally looks correct to me, but additional checks in datapath perhaps can
> be a concern, if not I am for getting the patch.

I don't think the calculation is a huge concern.

Acked-by: Chas Williams <chas3@att.com>

> 
>> ---
>> v2: add fixes lines
>> v3: fix buffer end calculation
>>
>>   drivers/net/bonding/rte_eth_bond_pmd.c | 9 +++++++--
>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/bonding/rte_eth_bond_pmd.c b/drivers/net/bonding/rte_eth_bond_pmd.c
>> index b0d191d..2b7f2b3 100644
>> --- a/drivers/net/bonding/rte_eth_bond_pmd.c
>> +++ b/drivers/net/bonding/rte_eth_bond_pmd.c
>> @@ -842,6 +842,7 @@ burst_xmit_l34_hash(struct rte_mbuf **buf, uint16_t nb_pkts,
>>   
>>   	for (i = 0; i < nb_pkts; i++) {
>>   		eth_hdr = rte_pktmbuf_mtod(buf[i], struct ether_hdr *);
>> +		size_t pkt_end = (size_t)eth_hdr + rte_pktmbuf_data_len(buf[i]);
>>   		proto = eth_hdr->ether_type;
>>   		vlan_offset = get_vlan_offset(eth_hdr, &proto);
>>   		l3hash = 0;
>> @@ -865,13 +866,17 @@ burst_xmit_l34_hash(struct rte_mbuf **buf, uint16_t nb_pkts,
>>   					tcp_hdr = (struct tcp_hdr *)
>>   						((char *)ipv4_hdr +
>>   							ip_hdr_offset);
>> -					l4hash = HASH_L4_PORTS(tcp_hdr);
>> +					if ((size_t)tcp_hdr + sizeof(*tcp_hdr)
>> +							< pkt_end)
>> +						l4hash = HASH_L4_PORTS(tcp_hdr);
>>   				} else if (ipv4_hdr->next_proto_id ==
>>   								IPPROTO_UDP) {
>>   					udp_hdr = (struct udp_hdr *)
>>   						((char *)ipv4_hdr +
>>   							ip_hdr_offset);
>> -					l4hash = HASH_L4_PORTS(udp_hdr);
>> +					if ((size_t)udp_hdr + sizeof(*udp_hdr)
>> +							< pkt_end)
>> +						l4hash = HASH_L4_PORTS(udp_hdr);
>>   				}
>>   			}
>>   		} else if  (rte_cpu_to_be_16(ETHER_TYPE_IPv6) == proto) {
>>
>