netdev - [PATCH V2 bpf] xdp: add NULL pointer check in __xdp

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Date:   Thu, 26 Jul 2018 00:09:50 +0900
From:   Taehee Yoo <ap420073@...il.com>
To:     daniel@...earbox.net, ast@...nel.org, bjorn.topel@...el.com
Cc:     brouer@...hat.com, netdev@...r.kernel.org,
        Taehee Yoo <ap420073@...il.com>
Subject: [PATCH V2 bpf] xdp: add NULL pointer check in __xdp_return()

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 <ap420073@...il.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