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

[Wolfram Sang <wsa@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 1627 bytes --]

On Thu, Nov 24, 2022 at 04:54:48PM +0800, Yang Yingliang wrote:
> 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>

The report seems correct to me, yet the solution is copying code a tad
too much IMO. I'll send another approach I'd suggest to spark some
discussion. Thanks for the report in any case!


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]