[PATCH v2 08/17] net/dpaa2: fix error packet dump crash and memory leak

[Maxime Leroy <maxime@leroys.fr>]

Fix three bugs in dump_err_pkts():

1. NULL pointer dereference: mbuf was checked for NULL but then
   dereferenced unconditionally on the next line.

2. Memory leak on multi-segment packets: the while loop walked
   mbuf to NULL, so the subsequent rte_pktmbuf_free(mbuf) was a
   no-op and the packet was never freed. Use a separate iterator
   variable and free the original mbuf pointer.

3. Segment index not reset between packets: variable i was
   initialized once at function scope and never reset inside the
   do/while loop, so hexdump titles had wrong segment numbers.
   Make it local to the multi-segment block.

Not tested, found by code review.

Fixes: 8b49427e73 ("net/dpaa2: add Rx error queue support")
Cc: stable@dpdk.org

Reported-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Maxime Leroy <maxime@leroys.fr>
---
 drivers/net/dpaa2/dpaa2_rxtx.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/net/dpaa2/dpaa2_rxtx.c b/drivers/net/dpaa2/dpaa2_rxtx.c
index 5a98f295a7..0de52cbef2 100644
--- a/drivers/net/dpaa2/dpaa2_rxtx.c
+++ b/drivers/net/dpaa2/dpaa2_rxtx.c
@@ -651,7 +651,7 @@ dump_err_pkts(struct dpaa2_queue *dpaa2_q)
 	const struct qbman_fd *fd;
 	struct qbman_pull_desc pulldesc;
 	struct rte_eth_dev_data *eth_data = dpaa2_q->eth_data;
-	uint32_t lcore_id = rte_lcore_id(), i = 0;
+	uint32_t lcore_id = rte_lcore_id();
 	void *v_addr, *hw_annot_addr;
 	struct dpaa2_fas *fas;
 	struct rte_mbuf *mbuf;
@@ -726,24 +726,27 @@ dump_err_pkts(struct dpaa2_queue *dpaa2_q)
 			DPAA2_GET_FD_OFFSET(fd), DPAA2_GET_FD_ERR(fd),
 			fas->status);
 
-		if (mbuf)
+		if (mbuf) {
 			__rte_mbuf_sanity_check(mbuf, 1);
-		if (mbuf->nb_segs > 1) {
-			while (mbuf) {
-				sprintf(title, "Payload seg[%d]", i);
-				rte_hexdump(stderr, title,
+			if (mbuf->nb_segs > 1) {
+				struct rte_mbuf *seg = mbuf;
+				int i = 0;
+
+				while (seg) {
+					sprintf(title, "Payload seg[%d]", i);
+					rte_hexdump(stderr, title,
+						(char *)seg->buf_addr + seg->data_off,
+						seg->data_len);
+					seg = seg->next;
+					i++;
+				}
+			} else {
+				rte_hexdump(stderr, "Payload",
 					(char *)mbuf->buf_addr + mbuf->data_off,
 					mbuf->data_len);
-				mbuf = mbuf->next;
-				i++;
 			}
-		} else {
-			rte_hexdump(stderr, "Payload",
-				(char *)mbuf->buf_addr + mbuf->data_off,
-				mbuf->data_len);
+			rte_pktmbuf_free(mbuf);
 		}
-
-		rte_pktmbuf_free(mbuf);
 		dq_storage++;
 		num_rx++;
 	} while (pending);
-- 
2.43.0