[PATCH V2 bpf] xdp: add NULL pointer check in __xdp_return()

[Taehee Yoo]

rhashtable_lookup() can return NULL. so that NULL pointer
check routine should be added.

Fixes: 02b55e5657c3 ("xdp: add MEM_TYPE_ZERO_COPY")
Signed-off-by: Taehee Yoo <ap420...@gmail.com>
---
V2 : add WARN_ON_ONCE when xa is NULL.

 net/core/xdp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/xdp.c b/net/core/xdp.c
index 9d1f220..786fdbe 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -345,7 +345,10 @@ static void __xdp_return(void *data, struct xdp_mem_info 
*mem, bool napi_direct,
                rcu_read_lock();
                /* mem->id is valid, checked in xdp_rxq_info_reg_mem_model() */
                xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
-               xa->zc_alloc->free(xa->zc_alloc, handle);
+               if (!xa)
+                       WARN_ON_ONCE(1);
+               else
+                       xa->zc_alloc->free(xa->zc_alloc, handle);
                rcu_read_unlock();
        default:
                /* Not possible, checked in xdp_rxq_info_reg_mem_model() */
-- 
2.9.3