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

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

[Yang Yingliang]

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);
 	ret = device_register(&hdev->cls_dev);
-	if (ret)
+	if (ret) {
+		put_device(&hdev->cls_dev);
 		return ret;
+	}
 
 	__module_get(THIS_MODULE);
 
-- 
2.25.1

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

[Leon Romanovsky]

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>

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

[Jakub Kicinski]

On Tue, 18 Oct 2022 15:58:38 +0300 Leon Romanovsky wrote:
> The change itself is ok.

Also the .release function is empty which is another bad smell?

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

Thanks!

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

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 18 Oct 2022 20:24:51 +0800 you 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]
> 
> [...]

Here is the summary with links:
  - [net] net: hns: fix possible memory leak in hnae_ae_register()
    https://git.kernel.org/netdev/net/c/ff2f5ec5d009

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

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

[Yang Yingliang]

On 2022/10/18 20:58, Leon Romanovsky wrote:
> 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.
Did you mean the 'void' can be removed ?
>
>>   	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.
hnae_ae_register() is called from hns_dsaf.ko(hns_dsaf_probe()), the
refcount of module hnae is already be got while loading hns_dsaf.ko
in resolve_symbol(),  so I think this can be removed.

Thanks,
Yang
>
> The change itself is ok.
>
> Thanks,
> Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
> .

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

[Yang Yingliang]

On 2022/10/20 8:28, Jakub Kicinski wrote:
> On Tue, 18 Oct 2022 15:58:38 +0300 Leon Romanovsky wrote:
>> The change itself is ok.
> Also the .release function is empty which is another bad smell?
The upper device (struct dsaf_device *dsaf_dev) is allocated by 
devm_kzalloc(),
so it's no need to free it in ->release().

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

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

[Jakub Kicinski]

On Thu, 20 Oct 2022 15:48:38 +0800 Yang Yingliang wrote:
> On 2022/10/20 8:28, Jakub Kicinski wrote:
> > On Tue, 18 Oct 2022 15:58:38 +0300 Leon Romanovsky wrote:  
> >> The change itself is ok.  
> >
> > Also the .release function is empty which is another bad smell?  
>
> The upper device (struct dsaf_device *dsaf_dev) is allocated by 
> devm_kzalloc(), so it's no need to free it in ->release().

Nah ah. devm_* is just for objects which tie their lifetime naturally
to the lifetime of the driver instance, IOW the device ->priv.

struct device allocated by the driver is not tied to that, it's 
a properly referenced object. I don't think that just because 
the driver that allocated it got ->remove()d you're safe to free
allocated struct devices.

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

[Yang Yingliang]

On 2022/10/21 3:43, Jakub Kicinski wrote:
> On Thu, 20 Oct 2022 15:48:38 +0800 Yang Yingliang wrote:
>> On 2022/10/20 8:28, Jakub Kicinski wrote:
>>> On Tue, 18 Oct 2022 15:58:38 +0300 Leon Romanovsky wrote:
>>>> The change itself is ok.
>>> Also the .release function is empty which is another bad smell?
>> The upper device (struct dsaf_device *dsaf_dev) is allocated by
>> devm_kzalloc(), so it's no need to free it in ->release().
> Nah ah. devm_* is just for objects which tie their lifetime naturally
> to the lifetime of the driver instance, IOW the device ->priv.
>
> struct device allocated by the driver is not tied to that, it's
> a properly referenced object. I don't think that just because
> the driver that allocated it got ->remove()d you're safe to free
> allocated struct devices.
In this driver, I see the 'cls_dev' is used as driver data and it 
unregistered
before got removed to free the device memory, I think it's safe for now.

Thanks,
Yang
> .

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

[Leon Romanovsky]

On Thu, Oct 20, 2022 at 03:45:17PM +0800, Yang Yingliang wrote:
> 
> On 2022/10/18 20:58, Leon Romanovsky wrote:
> > 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.
> Did you mean the 'void' can be removed ?

I mean that ethernet names are provided by netdev code and I don't
expect to see any dev_set_name() call in drivers/net/ethernet/* folders.

> > 
> > >   	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.
> hnae_ae_register() is called from hns_dsaf.ko(hns_dsaf_probe()), the
> refcount of module hnae is already be got while loading hns_dsaf.ko
> in resolve_symbol(),  so I think this can be removed.

Yes.

> 
> Thanks,
> Yang
> > 
> > The change itself is ok.
> > 
> > Thanks,
> > Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
> > .

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

[Leon Romanovsky]

On Fri, Oct 21, 2022 at 11:01:47AM +0800, Yang Yingliang wrote:
> 
> On 2022/10/21 3:43, Jakub Kicinski wrote:
> > On Thu, 20 Oct 2022 15:48:38 +0800 Yang Yingliang wrote:
> > > On 2022/10/20 8:28, Jakub Kicinski wrote:
> > > > On Tue, 18 Oct 2022 15:58:38 +0300 Leon Romanovsky wrote:
> > > > > The change itself is ok.
> > > > Also the .release function is empty which is another bad smell?
> > > The upper device (struct dsaf_device *dsaf_dev) is allocated by
> > > devm_kzalloc(), so it's no need to free it in ->release().
> > Nah ah. devm_* is just for objects which tie their lifetime naturally
> > to the lifetime of the driver instance, IOW the device ->priv.
> > 
> > struct device allocated by the driver is not tied to that, it's
> > a properly referenced object. I don't think that just because
> > the driver that allocated it got ->remove()d you're safe to free
> > allocated struct devices.
> In this driver, I see the 'cls_dev' is used as driver data and it
> unregistered
> before got removed to free the device memory, I think it's safe for now.

Empty release means reference counting doesn't really count anything.
According to your reply, cls_dev is protected from outside and its life
time bounded to upper level.

The thing is that you was expected to create that cls_dev when you did
device_initalization and release it with not-empty release function.

Thanks

> 
> Thanks,
> Yang
> > .