> From: Kumara Parameshwaran [mailto:kumaraparames...@gmail.com] > Sent: Sunday, 3 April 2022 13.51 > > As the minimum Ethernet frame size is 64 bytes, a 0 length > tcp payload without tcp options would be 54 bytes and hence > there would be padding. So it would be incorrect to use the > packet length to determine the tcp data length. > > Fixes: 1e4cf4d6d4fb ("gro: cleanup") > Cc: sta...@dpdk.org > > Signed-off-by: Kumara Parameshwaran <kparamesh...@vmware.com> > --- > v1: > Do not use packet length to determine the tcp data length as > the packet length could have padded bytes. This would lead > to addition of 0 length tcp packets into the GRO layer when > there ethernet fram is padded. > lib/gro/gro_tcp4.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/lib/gro/gro_tcp4.c b/lib/gro/gro_tcp4.c > index 7498c66..45e3f48 100644 > --- a/lib/gro/gro_tcp4.c > +++ b/lib/gro/gro_tcp4.c > @@ -198,7 +198,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt, > struct rte_tcp_hdr *tcp_hdr; > uint32_t sent_seq; > int32_t tcp_dl; > - uint16_t ip_id, hdr_len, frag_off; > + uint16_t ip_id, frag_off; > uint8_t is_atomic; > > struct tcp4_flow_key key; > @@ -217,7 +217,6 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt, > eth_hdr = rte_pktmbuf_mtod(pkt, struct rte_ether_hdr *); > ipv4_hdr = (struct rte_ipv4_hdr *)((char *)eth_hdr + pkt- > >l2_len); > tcp_hdr = (struct rte_tcp_hdr *)((char *)ipv4_hdr + pkt->l3_len); > - hdr_len = pkt->l2_len + pkt->l3_len + pkt->l4_len; > > /* > * Don't process the packet which has FIN, SYN, RST, PSH, URG, > ECE > @@ -229,7 +228,7 @@ gro_tcp4_reassemble(struct rte_mbuf *pkt, > * Don't process the packet whose payload length is less than or > * equal to 0. > */ > - tcp_dl = pkt->pkt_len - hdr_len; > + tcp_dl = rte_be_to_cpu_16(ipv4_hdr->total_length) - (pkt->l3_len > + pkt->l4_len); > if (tcp_dl <= 0) > return -1; > > -- > 2.7.4 >
Please confirm that this does not introduce a buffer overrun regarding malformed packets, e.g. a small packet with ipv4_hdr->total_length set to 65000. I haven't looked at the patch in context, so my concern may be irrelevant. -Morten
