[PATCH 5.4 058/109] nbd: Fix memory leak in nbd_add_socket

[Greg Kroah-Hartman]

From: Zheng Bin <zhengbi...@huawei.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+934037347002901b8...@syzkaller.appspotmail.com
Signed-off-by: Zheng Bin <zhengbi...@huawei.com>
Reviewed-by: Eric Biggers <ebigg...@google.com>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Sasha Levin <sas...@kernel.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 78181908f0df6..7b61d53ba050e 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1022,25 +1022,26 @@ static int nbd_add_socket(struct nbd_device *nbd, 
unsigned long arg,
             test_bit(NBD_RT_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);
@@ -1052,6 +1053,10 @@ 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