linux-kernel - [PATCH 4.14 022/125] nbd: Fix memory leak in nbd_add

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Date:   Mon, 20 Jul 2020 17:36:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+934037347002901b8d2a@...kaller.appspotmail.com,
        Zheng Bin <zhengbin13@...wei.com>,
        Eric Biggers <ebiggers@...gle.com>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 022/125] nbd: Fix memory leak in nbd_add_socket

From: Zheng Bin <zhengbin13@...wei.com>

[ Upstream commit 579dd91ab3a5446b148e7f179b6596b270dace46 ]

When adding first socket to nbd, if nsock's allocation failed, the data
structure member "config->socks" was reallocated, but the data structure
member "config->num_connections" was not updated. A memory leak will occur
then because the function "nbd_config_put" will free "config->socks" only
when "config->num_connections" is not zero.

Fixes: 03bf73c315ed ("nbd: prevent memory leak")
Reported-by: syzbot+934037347002901b8d2a@...kaller.appspotmail.com
Signed-off-by: Zheng Bin <zhengbin13@...wei.com>
Reviewed-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/block/nbd.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 8f56e6b2f114f..f22fad977c913 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -960,25 +960,26 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 	     test_bit(NBD_BOUND, &config->runtime_flags))) {
 		dev_err(disk_to_dev(nbd->disk),
 			"Device being setup by another task");
-		sockfd_put(sock);
-		return -EBUSY;
+		err = -EBUSY;
+		goto put_socket;
+	}
+
+	nsock = kzalloc(sizeof(*nsock), GFP_KERNEL);
+	if (!nsock) {
+		err = -ENOMEM;
+		goto put_socket;
 	}
 
 	socks = krealloc(config->socks, (config->num_connections + 1) *
 			 sizeof(struct nbd_sock *), GFP_KERNEL);
 	if (!socks) {
-		sockfd_put(sock);
-		return -ENOMEM;
+		kfree(nsock);
+		err = -ENOMEM;
+		goto put_socket;
 	}
 
 	config->socks = socks;
 
-	nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
-	if (!nsock) {
-		sockfd_put(sock);
-		return -ENOMEM;
-	}
-
 	nsock->fallback_index = -1;
 	nsock->dead = false;
 	mutex_init(&nsock->tx_lock);
@@ -990,6 +991,10 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 	atomic_inc(&config->live_connections);
 
 	return 0;
+
+put_socket:
+	sockfd_put(sock);
+	return err;
 }
 
 static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
-- 
2.25.1