2019-04-18 07:27:15

by Pan Bian

Subject: stm class: Fix possible double free

The function stm_register_device() calls put_device(&stm->dev) to
release allocated memory (in stm_device_release()) on error paths.
However, after that, the freed memory stm is released again, resulting
in a double free bug. There is a similar issue in the function
stm_source_register_device. This patch fixes these issues.

Signed-off-by: Pan Bian <[email protected]>
---
drivers/hwtracing/stm/core.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index c7ba8ac..cfb5c4d 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -886,8 +886,10 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
return -ENOMEM;

stm->major = register_chrdev(0, stm_data->name, &stm_fops);
- if (stm->major < 0)
- goto err_free;
+ if (stm->major < 0) {
+ vfree(stm);
+ return err;
+ }

device_initialize(&stm->dev);
stm->dev.devt = MKDEV(stm->major, 0);
@@ -933,8 +935,6 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,

/* matches device_initialize() above */
put_device(&stm->dev);
-err_free:
- vfree(stm);

return err;
}
@@ -1277,7 +1277,6 @@ int stm_source_register_device(struct device *parent,

err:
put_device(&src->dev);
- kfree(src);

return err;
}
--
2.7.4

2019-04-18 08:07:40

by Mukesh Ojha

Subject: Re: stm class: Fix possible double free

On 4/18/2019 12:52 PM, Pan Bian wrote:
> The function stm_register_device() calls put_device(&stm->dev) to
> release allocated memory (in stm_device_release()) on error paths.
> However, after that, the freed memory stm is released again, resulting
> in a double free bug. There is a similar issue in the function
> stm_source_register_device. This patch fixes these issues.
>
> Signed-off-by: Pan Bian <[email protected]>


Looks good to me.
Reviewed-by: Mukesh Ojha <[email protected]>

Cheers,
-Mukesh

> ---
> drivers/hwtracing/stm/core.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
> index c7ba8ac..cfb5c4d 100644
> --- a/drivers/hwtracing/stm/core.c
> +++ b/drivers/hwtracing/stm/core.c
> @@ -886,8 +886,10 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
> return -ENOMEM;
>
> stm->major = register_chrdev(0, stm_data->name, &stm_fops);
> - if (stm->major < 0)
> - goto err_free;
> + if (stm->major < 0) {
> + vfree(stm);
> + return err;
> + }
>
> device_initialize(&stm->dev);
> stm->dev.devt = MKDEV(stm->major, 0);
> @@ -933,8 +935,6 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
>
> /* matches device_initialize() above */
> put_device(&stm->dev);
> -err_free:
> - vfree(stm);
>
> return err;
> }
> @@ -1277,7 +1277,6 @@ int stm_source_register_device(struct device *parent,
>
> err:
> put_device(&src->dev);
> - kfree(src);
>
> return err;
> }