[PATCH] i2c: core: Fix possible memleak in i2c_new_client_device()

Yang Yingliang
2022-11-24T08:57:07Z

I got memory leak as follows when doing fault injection test:

unreferenced object 0xffff888014aec078 (size 8):
comm "xrun", pid 356, jiffies 4294910619 (age 16.332s)
hex dump (first 8 bytes):
31 2d 30 30 31 63 00 00 1-001c..
backtrace:
[<00000000eb56c0a9>] __kmalloc_track_caller+0x1a6/0x300
[<000000000b220ea3>] kvasprintf+0xad/0x140
[<00000000b83203e5>] kvasprintf_const+0x62/0x190
[<000000002a5eab37>] kobject_set_name_vargs+0x56/0x140
[<00000000300ac279>] dev_set_name+0xb0/0xe0
[<00000000b66ebd6f>] i2c_new_client_device+0x7e4/0x9a0

If device_register() returns error in i2c_new_client_device(),
the name allocated by i2c_dev_set_name() need be freed. As
comment of device_register() says, it should use put_device()
to give up the reference in the error path.

Moving i2c_dev_set_name() to front of device_register(), so
it's managed by device core, then call put_device(), when the
refcount is 0, the name will be freed in kobject_cleanup() and
the 'client' will be freed in i2c_client_dev_release().

Because the 'client' is freed by calling put_device(), so it
don't need goto error label, release other resources before
put_device() and return directly.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
drivers/i2c/i2c-core-base.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index b4edf10e8fd0..161bf28f2d87 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -954,7 +954,6 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
client->dev.fwnode = info->fwnode;

device_enable_async_suspend(&client->dev);
- i2c_dev_set_name(adap, client, info);

if (info->swnode) {
status = device_add_software_node(&client->dev, info->swnode);
@@ -966,17 +965,23 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
}
}

+ i2c_dev_set_name(adap, client, info);
status = device_register(&client->dev);
- if (status)
- goto out_remove_swnode;
+ if (status) {
+ device_remove_software_node(&client->dev);
+ of_node_put(info->of_node);
+ dev_err(&adap->dev,
+ "Failed to register i2c client %s at 0x%02x (%d)\n",
+ client->name, client->addr, status);
+ put_device(&client->dev);
+ return ERR_PTR(status);
+ }

dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
client->name, dev_name(&client->dev));

return client;

-out_remove_swnode:
- device_remove_software_node(&client->dev);
out_err_put_of_node:
of_node_put(info->of_node);
out_err:
--
2.25.1