Re: [PATCH] nbd: Fix memory leak in nbd_add_socket
From: Eric Biggers <ebiggers@kernel.org>
Date: 2020-06-28 15:58:48
Subsystem:
block layer, network block device (nbd), the rest · Maintainers:
Jens Axboe, Josef Bacik, Linus Torvalds
On Thu, Jun 25, 2020 at 12:16:33AM +0000, Chaitanya Kulkarni wrote:
On 6/12/20 1:57 AM, Zheng Bin wrote:quoted
nbd_add_socket socks = krealloc(num_connections+1) -->if num_connections is 0, alloc 1 nsock = kzalloc -->If fail, will return nbd_config_put if (config->num_connections) -->0, not free kfree(config->socks) Thus memleak happens, this patch fixes that. Signed-off-by: Zheng Bin<redacted>
This appears to address the syzbot report "memory leak in nbd_add_socket" https://syzkaller.appspot.com/bug?id=08283193956ab772623e65242b3ed6d0e7c7d9ce Can you please add: Reported-by: syzbot+934037347002901b8d2a@syzkaller.appspotmail.com
quoted hunk ↗ jump to hunk
Not an nbd expert but wouldn't it be easier use following which matches the + 1 in the nbd_add_socket() :-diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 01794cd2b6ca..e67c790039c9 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c@@ -1209,9 +1209,9 @@ static void nbd_config_put(struct nbd_device *nbd) device_remove_file(disk_to_dev(nbd->disk),&pid_attr); nbd->task_recv = NULL; nbd_clear_sock(nbd); - if (config->num_connections) { + if (config->num_connections + 1) { int i; - for (i = 0; i < config->num_connections; i++) { + for (i = 0; i < (config->num_connections + 1); i++) { sockfd_put(config->socks[i]->sock); kfree(config->socks[i]); }
That looks wrong. The + 1 is just nbd_add_socket() preparing to append an entry to the array. Why not just check whether the pointer is NULL or not:
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 43cff01a5a67..cb8e86174edb 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c@@ -1206,7 +1206,7 @@ static void nbd_config_put(struct nbd_device *nbd) device_remove_file(disk_to_dev(nbd->disk), &pid_attr); nbd->task_recv = NULL; nbd_clear_sock(nbd); - if (config->num_connections) { + if (config->socks) { int i; for (i = 0; i < config->num_connections; i++) { sockfd_put(config->socks[i]->sock);