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

Wolfram Sang
2023-09-29T09:16:05Z

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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!

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