linux-kernel - [PATCH] sock: fix potential memory leak in proto

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Message-Id: <1566178556-46071-1-git-send-email-zhang.lin16@zte.com.cn>
Date:   Mon, 19 Aug 2019 09:35:56 +0800
From:   zhanglin <zhang.lin16@....com.cn>
To:     davem@...emloft.net
Cc:     ast@...nel.org, daniel@...earbox.net, kafai@...com,
        songliubraving@...com, yhs@...com, willemb@...gle.com,
        edumazet@...gle.com, deepa.kernel@...il.com, arnd@...db.de,
        dh.herrmann@...il.com, gnault@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        xue.zhihong@....com.cn, wang.yi59@....com.cn,
        jiang.xuexin@....com.cn, zhanglin <zhang.lin16@....com.cn>
Subject: [PATCH] sock: fix potential memory leak in proto_register()

If protocols registered exceeded PROTO_INUSE_NR, prot will be
added to proto_list, but no available bit left for prot in
proto_inuse_idx.

Signed-off-by: zhanglin <zhang.lin16@....com.cn>
---
 net/core/sock.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index bc3512f230a3..25388d429f6a 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3139,16 +3139,17 @@ static __init int net_inuse_init(void)
 
 core_initcall(net_inuse_init);
 
-static void assign_proto_idx(struct proto *prot)
+static int assign_proto_idx(struct proto *prot)
 {
 	prot->inuse_idx = find_first_zero_bit(proto_inuse_idx, PROTO_INUSE_NR);
 
 	if (unlikely(prot->inuse_idx == PROTO_INUSE_NR - 1)) {
 		pr_err("PROTO_INUSE_NR exhausted\n");
-		return;
+		return -ENOSPC;
 	}
 
 	set_bit(prot->inuse_idx, proto_inuse_idx);
+	return 0;
 }
 
 static void release_proto_idx(struct proto *prot)
@@ -3243,18 +3244,24 @@ int proto_register(struct proto *prot, int alloc_slab)
 	}
 
 	mutex_lock(&proto_list_mutex);
+	if (assign_proto_idx(prot)) {
+		mutex_unlock(&proto_list_mutex);
+		goto out_free_timewait_sock_slab_name;
+	}
 	list_add(&prot->node, &proto_list);
-	assign_proto_idx(prot);
 	mutex_unlock(&proto_list_mutex);
 	return 0;
 
 out_free_timewait_sock_slab_name:
-	kfree(prot->twsk_prot->twsk_slab_name);
+	if (alloc_slab && prot->twsk_prot)
+		kfree(prot->twsk_prot->twsk_slab_name);
 out_free_request_sock_slab:
-	req_prot_cleanup(prot->rsk_prot);
+	if (alloc_slab) {
+		req_prot_cleanup(prot->rsk_prot);
 
-	kmem_cache_destroy(prot->slab);
-	prot->slab = NULL;
+		kmem_cache_destroy(prot->slab);
+		prot->slab = NULL;
+	}
 out:
 	return -ENOBUFS;
 }
-- 
2.17.1