Re: [PATCH v2 1/2] net/af_xdp: fix use after free in af_xdp_tx_zc()

[Maryam Tahhan]

On 16/01/2025 17:51, Ariel Otilibili wrote:
tx_bytes is computed after both legs are tested. This might
produce a use after memory free.

The computation is now moved into each leg.

Bugzilla ID: 1440
Fixes: d8a210774e1d ("net/af_xdp: support unaligned umem chunks")
Signed-off-by: Ariel Otilibili <ariel.otilib...@6wind.com>
---
  drivers/net/af_xdp/rte_eth_af_xdp.c | 4 ++--
  1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c 
b/drivers/net/af_xdp/rte_eth_af_xdp.c
index 814398ba4b44..4326a29f7042 100644
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -574,6 +574,7 @@ af_xdp_tx_zc(void *queue, struct rte_mbuf **bufs, uint16_t 
nb_pkts)
                                        umem->mb_pool->header_size;
                        offset = offset << XSK_UNALIGNED_BUF_OFFSET_SHIFT;
                        desc->addr = addr | offset;
+                       tx_bytes += mbuf->pkt_len;
                        count++;
                } else {
                        struct rte_mbuf *local_mbuf =
@@ -601,11 +602,10 @@ af_xdp_tx_zc(void *queue, struct rte_mbuf **bufs, 
uint16_t nb_pkts)
                        desc->addr = addr | offset;
                        rte_memcpy(pkt, rte_pktmbuf_mtod(mbuf, void *),
                                        desc->len);
+                       tx_bytes += mbuf->pkt_len;
                        rte_pktmbuf_free(mbuf);
                        count++;
                }
-
-               tx_bytes += mbuf->pkt_len;
        }
  
  out:

I think that you could've just set tx_bytes to the desc->len as this is 
being set in all scenarios...

tx_bytes += desc->len;