| Message ID | 20200622112001.105047-1-zhengbin13@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] nbd: Fix memory leak in nbd_add_socket | expand |
> When adding first socket to nbd, … Can the term “network block device” matter for this change description? > … A memory leak will occur > then because the function "nbd_config_put" will free "config->socks" only > when "config->num_connections" is not zero. Will an additional imperative wording be helpful for the commit message? https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?id=625d3449788f85569096780592549d0340e9c0c7#n151 Regards, Markus … > +++ b/drivers/block/nbd.c > @@ -1033,25 +1033,26 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg, … > + if (!nsock) { > + err = -ENOMEM; > + goto put_socket; > } … > return 0; > + I find that the exception handling can be improved a bit more by adding another jump target. +e_nomem: + err = -ENOMEM; > +put_socket: > + sockfd_put(sock); > + return err; > } Would you like to apply any further fine-tuning? Regards, Markus
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 43cff01a5a67..ce7e9f223b20 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1033,25 +1033,26 @@ 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); @@ -1063,6 +1064,10 @@ 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)
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") Signed-off-by: Zheng Bin <zhengbin13@huawei.com> --- v1->v2: improve change description v2->v3: fix some code style issues, improve change description, thanks to Markus for the review. drivers/block/nbd.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) -- 2.26.0.106.g9fadedd