[dpdk-dev] [PATCH v2] ring: fix use after free in ring release

[Yunjian Wang <wangyunjian@huawei.com>]

After the memzone is freed, it is not removed from the 'rte_ring_tailq'.
If rte_ring_lookup is called at this time, it will cause a use-after-free
problem. This change prevents that from happening.

Fixes: 4e32101f9b01 ("ring: support freeing")
Cc: stable@dpdk.org

Suggested-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
---
v2: update code suggested by Honnappa Nagarahalli
---
 lib/ring/rte_ring.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/lib/ring/rte_ring.c b/lib/ring/rte_ring.c
index 8ed455043d..2755323b8a 100644
--- a/lib/ring/rte_ring.c
+++ b/lib/ring/rte_ring.c
@@ -333,11 +333,6 @@ rte_ring_free(struct rte_ring *r)
 		return;
 	}
 
-	if (rte_memzone_free(r->memzone) != 0) {
-		RTE_LOG(ERR, RING, "Cannot free memory\n");
-		return;
-	}
-
 	ring_list = RTE_TAILQ_CAST(rte_ring_tailq.head, rte_ring_list);
 	rte_mcfg_tailq_write_lock();
 
@@ -354,6 +349,9 @@ rte_ring_free(struct rte_ring *r)
 
 	TAILQ_REMOVE(ring_list, te, next);
 
+	if (rte_memzone_free(r->memzone) != 0)
+		RTE_LOG(ERR, RING, "Cannot free memory\n");
+
 	rte_mcfg_tailq_write_unlock();
 
 	rte_free(te);
-- 
2.33.0