[PATCH] net/netvsc: fix event buffer leak on realloc failure

[Chen Zhao <ch3nzhao@gmail.com>]

rte_realloc() failure overwrites event_buf and leaks the old allocation.
Save the old pointer and free it on failure before resetting event_sz.

Fixes: 1f2766b7ee02 ("net/netvsc: resize event buffer as needed")
Cc: sthemmin@microsoft.com
Cc: stable@dpdk.org
Signed-off-by: Chen Zhao <ch3nzhao@gmail.com>
---
 .mailmap                     | 1 +
 drivers/net/netvsc/hn_rxtx.c | 8 ++++++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/.mailmap b/.mailmap
index 6d9e262cfb..deae6514dd 100644
--- a/.mailmap
+++ b/.mailmap
@@ -267,6 +267,7 @@ Charles Myers <charles.myers@spirent.com>
 Charles Stoll <charles.stoll@intel.com>
 Chas Williams <3chas3@gmail.com> <chas3@att.com>
 Chas Williams <3chas3@gmail.com> <ciwillia@brocade.com>
+Chen Zhao <ch3nzhao@gmail.com>
 Chenbo Xia <chenbox@nvidia.com> <chenbo.xia@intel.com>
 Cheng Jiang <honest.jiang@foxmail.com> <cheng1.jiang@intel.com>
 Cheng Liu <liucheng11@huawei.com>
diff --git a/drivers/net/netvsc/hn_rxtx.c b/drivers/net/netvsc/hn_rxtx.c
index 6f536610f2..4db6c933c9 100644
--- a/drivers/net/netvsc/hn_rxtx.c
+++ b/drivers/net/netvsc/hn_rxtx.c
@@ -1131,15 +1131,19 @@ uint32_t hn_process_events(struct hn_data *hv, uint16_t queue_id,
 
 		if (unlikely(ret == -ENOBUFS)) {
 			/* event buffer not large enough to read ring */
+			void *old_buf = rxq->event_buf;
 
 			PMD_DRV_LOG(DEBUG,
 				    "event buffer expansion (need %u)", len);
 			rxq->event_sz = len + len / 4;
-			rxq->event_buf = rte_realloc(rxq->event_buf, rxq->event_sz,
+			rxq->event_buf = rte_realloc(old_buf, rxq->event_sz,
 						     RTE_CACHE_LINE_SIZE);
 			if (rxq->event_buf)
 				goto retry;
-			/* out of memory, no more events now */
+			/*
+			 * out of memory, free the old buffer, no more events now
+			 */
+			rte_free(old_buf);
 			rxq->event_sz = 0;
 			break;
 		}
-- 
2.43.0