Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Kangjie Lu <kjlu@umn.edu>
To:     kjlu@umn.edu
Cc:     pakki001@umn.edu, Josef Bacik <josef@toxicpanda.com>,
        Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        nbd@other.debian.org, linux-kernel@vger.kernel.org
Subject: [PATCH] block: nbd: fix a missing check for nla_nest_start
Date:   Fri, 15 Mar 2019 01:31:38 -0500
Message-Id: <20190315063138.17666-1-kjlu@umn.edu>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

nla_nest_start may fail and thus deserves a check.

The fix inserts such a check and exits gracefully in case it
fails.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
---
 drivers/block/nbd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 7c9a949e876b..810c8c20b142 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -2099,6 +2099,10 @@ static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	dev_list = nla_nest_start(reply, NBD_ATTR_DEVICE_LIST);
+	if (!dev_list) {
+		nlmsg_free(reply);
+		goto out;
+	}
 	if (index == -1) {
 		ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
 		if (ret) {
-- 
2.17.1