[PATCH AUTOSEL 6.6 3/7] i2c: fix memleak in i2c_new_client_device()

From: Sasha Levin
Date: Sun Nov 12 2023 - 08:23:59 EST


From: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>

[ Upstream commit 6af79f7fe748fe6a3c5c3a63d7f35981a82c2769 ]

Yang Yingliang reported a memleak:
===

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.

===
I think this solution is less intrusive and more robust than he
originally proposed solutions, though.

Reported-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
Closes: http://patchwork.ozlabs.org/project/linux-i2c/patch/20221124085448.3620240-1-yangyingliang@xxxxxxxxxx/
Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/i2c/i2c-core-base.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 60746652fd525..7f30bcceebaed 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -931,8 +931,9 @@ int i2c_dev_irq_from_resources(const struct resource *resources,
struct i2c_client *
i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
{
- struct i2c_client *client;
- int status;
+ struct i2c_client *client;
+ bool need_put = false;
+ int status;

client = kzalloc(sizeof *client, GFP_KERNEL);
if (!client)
@@ -970,7 +971,6 @@ 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);
@@ -982,6 +982,7 @@ 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;
@@ -993,6 +994,7 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf

out_remove_swnode:
device_remove_software_node(&client->dev);
+ need_put = true;
out_err_put_of_node:
of_node_put(info->of_node);
out_err:
@@ -1000,7 +1002,10 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
"Failed to register i2c client %s at 0x%02x (%d)\n",
client->name, client->addr, status);
out_err_silent:
- kfree(client);
+ if (need_put)
+ put_device(&client->dev);
+ else
+ kfree(client);
return ERR_PTR(status);
}
EXPORT_SYMBOL_GPL(i2c_new_client_device);
--
2.42.0