2019-01-04 06:27:36

by liujian (CE)

Subject: [PATCH v2] driver: uio: fix possible memory leak and use-after-free in __uio_register_device

'idev' is malloced in __uio_register_device() and leak free it before
leaving from the uio_get_minor() error handing case, it will cause
memory leak.

Also, in uio_dev_add_attributes() error handing case, idev is used after
device_unregister(), in which 'idev' has been released, touch idev cause
use-after-free.

Fixes: a93e7b331568 ("uio: Prevent device destruction while fds are open")
Fixes: e6789cd3dfb5 ("uio: Simplify uio error path by using devres
functions")
Signed-off-by: liujian <[email protected]>
---
v1->v2:
change git log and fix code

drivers/uio/uio.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 1313422..be2a943 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -940,9 +940,12 @@ int __uio_register_device(struct module *owner,
atomic_set(&idev->event, 0);

ret = uio_get_minor(idev);
- if (ret)
+ if (ret) {
+ kfree(idev);
return ret;
+ }

+ device_initialize(&idev->dev);
idev->dev.devt = MKDEV(uio_major, idev->minor);
idev->dev.class = &uio_class;
idev->dev.parent = parent;
@@ -953,7 +956,7 @@ int __uio_register_device(struct module *owner,
if (ret)
goto err_device_create;

- ret = device_register(&idev->dev);
+ ret = device_add(&idev->dev);
if (ret)
goto err_device_create;

@@ -985,9 +988,10 @@ int __uio_register_device(struct module *owner,
err_request_irq:
uio_dev_del_attributes(idev);
err_uio_dev_add_attributes:
- device_unregister(&idev->dev);
+ device_del(&idev->dev);
err_device_create:
uio_free_minor(idev);
+ put_device(&idev->dev);
return ret;
}
EXPORT_SYMBOL_GPL(__uio_register_device);
--
2.7.4

2019-01-06 20:18:20

by Hamish Martin

Subject: Re: [PATCH v2] driver: uio: fix possible memory leak and use-after-free in __uio_register_device

On Fri, 2019-01-04 at 22:19 +0800, liujian wrote:
> 'idev' is malloced in __uio_register_device() and leak free it before
> leaving from the uio_get_minor() error handing case, it will cause
> memory leak.
>
> Also, in uio_dev_add_attributes() error handing case, idev is used
> after
> device_unregister(), in which 'idev' has been released, touch idev
> cause
> use-after-free.
>
> Fixes: a93e7b331568 ("uio: Prevent device destruction while fds are
> open")
> Fixes: e6789cd3dfb5 ("uio: Simplify uio error path by using devres
> functions")
> Signed-off-by: liujian <[email protected]>
> ---
> v1->v2:
> change git log and fix code
>
>  drivers/uio/uio.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 1313422..be2a943 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -940,9 +940,12 @@ int __uio_register_device(struct module *owner,
>   atomic_set(&idev->event, 0);
>  
>   ret = uio_get_minor(idev);
> - if (ret)
> + if (ret) {
> + kfree(idev);
>   return ret;
> + }
>  
> + device_initialize(&idev->dev);
>   idev->dev.devt = MKDEV(uio_major, idev->minor);
>   idev->dev.class = &uio_class;
>   idev->dev.parent = parent;
> @@ -953,7 +956,7 @@ int __uio_register_device(struct module *owner,
>   if (ret)
>   goto err_device_create;
>  
> - ret = device_register(&idev->dev);
> + ret = device_add(&idev->dev);
>   if (ret)
>   goto err_device_create;
>  
> @@ -985,9 +988,10 @@ int __uio_register_device(struct module *owner,
>  err_request_irq:
>   uio_dev_del_attributes(idev);
>  err_uio_dev_add_attributes:
> - device_unregister(&idev->dev);
> + device_del(&idev->dev);
>  err_device_create:
>   uio_free_minor(idev);
> + put_device(&idev->dev);
>   return ret;
>  }
>  EXPORT_SYMBOL_GPL(__uio_register_device);

Looks good to me. Thanks for dealing with those issues.
Reviewed-by: Hamish Martin <[email protected]>

2019-01-07 16:55:57

by Greg Kroah-Hartman

Subject: Re: [PATCH v2] driver: uio: fix possible memory leak and use-after-free in __uio_register_device

On Fri, Jan 04, 2019 at 10:19:08PM +0800, liujian wrote:
> 'idev' is malloced in __uio_register_device() and leak free it before
> leaving from the uio_get_minor() error handing case, it will cause
> memory leak.
>
> Also, in uio_dev_add_attributes() error handing case, idev is used after
> device_unregister(), in which 'idev' has been released, touch idev cause
> use-after-free.
>
> Fixes: a93e7b331568 ("uio: Prevent device destruction while fds are open")
> Fixes: e6789cd3dfb5 ("uio: Simplify uio error path by using devres functions")
> Signed-off-by: liujian <[email protected]>
> Reviewed-by: Hamish Martin <[email protected]>
> ---
> v1->v2:
> change git log and fix code
>
> drivers/uio/uio.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 1313422..be2a943 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -940,9 +940,12 @@ int __uio_register_device(struct module *owner,
> atomic_set(&idev->event, 0);
>
> ret = uio_get_minor(idev);
> - if (ret)
> + if (ret) {
> + kfree(idev);
> return ret;
> + }
>
> + device_initialize(&idev->dev);
> idev->dev.devt = MKDEV(uio_major, idev->minor);
> idev->dev.class = &uio_class;
> idev->dev.parent = parent;
> @@ -953,7 +956,7 @@ int __uio_register_device(struct module *owner,
> if (ret)
> goto err_device_create;
>
> - ret = device_register(&idev->dev);
> + ret = device_add(&idev->dev);
> if (ret)
> goto err_device_create;
>
> @@ -985,9 +988,10 @@ int __uio_register_device(struct module *owner,
> err_request_irq:
> uio_dev_del_attributes(idev);
> err_uio_dev_add_attributes:
> - device_unregister(&idev->dev);
> + device_del(&idev->dev);
> err_device_create:
> uio_free_minor(idev);
> + put_device(&idev->dev);

device_del() and then put_device()? I don't think that's a correct
error cleanup path do you?

Please fix one thing at a time here also, this should be a a patch
series, right?

thanks,

greg k-h

2019-01-08 02:53:01

by liujian (CE)

Subject: RE: [PATCH v2] driver: uio: fix possible memory leak and use-after-free in __uio_register_device

> -----Original Message-----
> From: Greg KH [mailto:[email protected]]
> Sent: Tuesday, January 08, 2019 12:13 AM
> To: liujian (CE) <[email protected]>
> Cc: [email protected]; [email protected];
> [email protected]
> Subject: Re: [PATCH v2] driver: uio: fix possible memory leak and use-after-free
> in __uio_register_device
>
> On Fri, Jan 04, 2019 at 10:19:08PM +0800, liujian wrote:
> > 'idev' is malloced in __uio_register_device() and leak free it before
> > leaving from the uio_get_minor() error handing case, it will cause
> > memory leak.
> >
> > Also, in uio_dev_add_attributes() error handing case, idev is used
> > after device_unregister(), in which 'idev' has been released, touch
> > idev cause use-after-free.
> >
> > Fixes: a93e7b331568 ("uio: Prevent device destruction while fds are
> > open")
> > Fixes: e6789cd3dfb5 ("uio: Simplify uio error path by using devres
> > functions")
> > Signed-off-by: liujian <[email protected]>
> > Reviewed-by: Hamish Martin <[email protected]>
> > ---
> > v1->v2:
> > change git log and fix code
> >
> > drivers/uio/uio.c | 10 +++++++---
> > 1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index
> > 1313422..be2a943 100644
> > --- a/drivers/uio/uio.c
> > +++ b/drivers/uio/uio.c
> > @@ -940,9 +940,12 @@ int __uio_register_device(struct module *owner,
> > atomic_set(&idev->event, 0);
> >
> > ret = uio_get_minor(idev);
> > - if (ret)
> > + if (ret) {
> > + kfree(idev);
> > return ret;
> > + }
> >
> > + device_initialize(&idev->dev);
> > idev->dev.devt = MKDEV(uio_major, idev->minor);
> > idev->dev.class = &uio_class;
> > idev->dev.parent = parent;
> > @@ -953,7 +956,7 @@ int __uio_register_device(struct module *owner,
> > if (ret)
> > goto err_device_create;
> >
> > - ret = device_register(&idev->dev);
> > + ret = device_add(&idev->dev);
> > if (ret)
> > goto err_device_create;
> >
> > @@ -985,9 +988,10 @@ int __uio_register_device(struct module *owner,
> > err_request_irq:
> > uio_dev_del_attributes(idev);
> > err_uio_dev_add_attributes:
> > - device_unregister(&idev->dev);
> > + device_del(&idev->dev);
> > err_device_create:
> > uio_free_minor(idev);
> > + put_device(&idev->dev);
>
> device_del() and then put_device()? I don't think that's a correct error
> cleanup path do you?
>
In err_uio_dev_add_attributes error handling case, device_unregister() will call put_device(), and idev will be released in put_device()
Then in err_device_create error handling case, uio_free_minor() will trigger use-after-free

Now, divide device_register() into device_initialize() and device_add(), and divide device_unregister() into device_del() and put_device().
Call uio_free_minor() and then call put_device() to avoid use-after-free

> Please fix one thing at a time here also, this should be a a patch series, right?
>
Yes, I will do, thanks~

Best Regards,
Liujian

> thanks,
>
> greg k-h