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SubjectRe: [PATCH] ptp: Fix possible memory leak in ptp_clock_register()
On Wed, 20 Oct 2021 16:18:34 +0800 Yang Yingliang wrote:
> I got memory leak as follows when doing fault injection test:
>
> unreferenced object 0xffff88800906c618 (size 8):
> comm "i2c-idt82p33931", pid 4421, jiffies 4294948083 (age 13.188s)
> hex dump (first 8 bytes):
> 70 74 70 30 00 00 00 00 ptp0....
> backtrace:
> [<00000000312ed458>] __kmalloc_track_caller+0x19f/0x3a0
> [<0000000079f6e2ff>] kvasprintf+0xb5/0x150
> [<0000000026aae54f>] kvasprintf_const+0x60/0x190
> [<00000000f323a5f7>] kobject_set_name_vargs+0x56/0x150
> [<000000004e35abdd>] dev_set_name+0xc0/0x100
> [<00000000f20cfe25>] ptp_clock_register+0x9f4/0xd30 [ptp]
> [<000000008bb9f0de>] idt82p33_probe.cold+0x8b6/0x1561 [ptp_idt82p33]
>
> When posix_clock_register() returns an error, the name allocated
> in dev_set_name() will be leaked, the put_device() should be used
> to give up the device reference, then the name will be freed in
> kobject_cleanup() and other memory will be freed in ptp_clock_release().
>
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Fixes: a33121e5487b ("ptp: fix the race between the release of ptp_clock and cdev")
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>

> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> index 4dfc52e06704..7fd02aabd79a 100644
> --- a/drivers/ptp/ptp_clock.c
> +++ b/drivers/ptp/ptp_clock.c
> @@ -283,15 +283,22 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
> /* Create a posix clock and link it to the device. */
> err = posix_clock_register(&ptp->clock, &ptp->dev);
> if (err) {
> + if (ptp->pps_source)
> + pps_unregister_source(ptp->pps_source);
> +
> + kfree(ptp->vclock_index);

I think the way ptp->vclock_index is freed is also buggy.

It's accessed from sysfs so it should be freed from the release
function, not directly here or in ptp_clock_unregister(), right?

If that makes sense please submit a separate fix for the issue.

> + if (ptp->kworker)
> + kthread_destroy_worker(ptp->kworker);
> +
> + put_device(&ptp->dev);
> +
> pr_err("failed to create posix clock\n");
> - goto no_clock;
> + return ERR_PTR(err);
> }
>
> return ptp;
>
> -no_clock:
> - if (ptp->pps_source)
> - pps_unregister_source(ptp->pps_source);
> no_pps:
> ptp_cleanup_pin_groups(ptp);
> no_pin_groups:

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