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Subject[PATCH 5.4 058/109] nbd: Fix memory leak in nbd_add_socket
Date
From: Zheng Bin <zhengbin13@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+934037347002901b8d2a@syzkaller.appspotmail.com
Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@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


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