Re: [PATCH net] net: hns: fix possible memory leak in hnae_ae_register()

[Leon Romanovsky <leon@kernel.org>]

On Tue, Oct 18, 2022 at 08:24:51PM +0800, Yang Yingliang wrote:
> Inject fault while probing module, if device_register() fails,
> but the refcount of kobject is not decreased to 0, the name
> allocated in dev_set_name() is leaked. Fix this by calling
> put_device(), so that name can be freed in callback function
> kobject_cleanup().
> 
> unreferenced object 0xffff00c01aba2100 (size 128):
>   comm "systemd-udevd", pid 1259, jiffies 4294903284 (age 294.152s)
>   hex dump (first 32 bytes):
>     68 6e 61 65 30 00 00 00 18 21 ba 1a c0 00 ff ff  hnae0....!......
>     00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>   backtrace:
>     [<0000000034783f26>] slab_post_alloc_hook+0xa0/0x3e0
>     [<00000000748188f2>] __kmem_cache_alloc_node+0x164/0x2b0
>     [<00000000ab0743e8>] __kmalloc_node_track_caller+0x6c/0x390
>     [<000000006c0ffb13>] kvasprintf+0x8c/0x118
>     [<00000000fa27bfe1>] kvasprintf_const+0x60/0xc8
>     [<0000000083e10ed7>] kobject_set_name_vargs+0x3c/0xc0
>     [<000000000b87affc>] dev_set_name+0x7c/0xa0
>     [<000000003fd8fe26>] hnae_ae_register+0xcc/0x190 [hnae]
>     [<00000000fe97edc9>] hns_dsaf_ae_init+0x9c/0x108 [hns_dsaf]
>     [<00000000c36ff1eb>] hns_dsaf_probe+0x548/0x748 [hns_dsaf]
> 
> Fixes: 6fe6611ff275 ("net: add Hisilicon Network Subsystem hnae framework support")
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---
>  drivers/net/ethernet/hisilicon/hns/hnae.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/hisilicon/hns/hnae.c b/drivers/net/ethernet/hisilicon/hns/hnae.c
> index 00fafc0f8512..430eccea8e5e 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hnae.c
> +++ b/drivers/net/ethernet/hisilicon/hns/hnae.c
> @@ -419,8 +419,10 @@ int hnae_ae_register(struct hnae_ae_dev *hdev, struct module *owner)
>  	hdev->cls_dev.release = hnae_release;
>  	(void)dev_set_name(&hdev->cls_dev, "hnae%d", hdev->id);
              ^^^^^^^^^^^^ this is unexpected in netdev code.

>  	ret = device_register(&hdev->cls_dev);
> -	if (ret)
> +	if (ret) {
> +		put_device(&hdev->cls_dev);
>  		return ret;
> +	}
>  
>  	__module_get(THIS_MODULE);
        ^^^^^^^^ I'm curious why? I don't see why you need this.

The change itself is ok.

Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>