[PATCH] drm/amd/display: fix crash/reboot while accessing sysfs files

[Harry Wentland]

On 2020-09-17 4:54 a.m., Shirish S wrote:
> read/writes to aux_dpcd_* sysfs entries leads to system
> reboot or hang.
> Hence fix the handling of input data and reporting of errors
> appropriately to the user space.
> 
> Signed-off-by: Shirish S <shirish.s at amd.com>

Reviewed-by: Harry Wentland <harry.wentland at amd.com>

Harry

> ---
>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c  | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
> index 004cd8d38214..8cd646eef096 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
> @@ -908,7 +908,7 @@ static ssize_t dp_dpcd_address_write(struct file *f, const char __user *buf,
>   	struct amdgpu_dm_connector *connector = file_inode(f)->i_private;
>   
>   	if (size < sizeof(connector->debugfs_dpcd_address))
> -		return 0;
> +		return -EINVAL;
>   
>   	r = copy_from_user(&connector->debugfs_dpcd_address,
>   			buf, sizeof(connector->debugfs_dpcd_address));
> @@ -923,7 +923,7 @@ static ssize_t dp_dpcd_size_write(struct file *f, const char __user *buf,
>   	struct amdgpu_dm_connector *connector = file_inode(f)->i_private;
>   
>   	if (size < sizeof(connector->debugfs_dpcd_size))
> -		return 0;
> +		return -EINVAL;
>   
>   	r = copy_from_user(&connector->debugfs_dpcd_size,
>   			buf, sizeof(connector->debugfs_dpcd_size));
> @@ -943,8 +943,8 @@ static ssize_t dp_dpcd_data_write(struct file *f, const char __user *buf,
>   	struct dc_link *link = connector->dc_link;
>   	uint32_t write_size = connector->debugfs_dpcd_size;
>   
> -	if (size < write_size)
> -		return 0;
> +	if (!write_size || size < write_size)
> +		return -EINVAL;
>   
>   	data = kzalloc(write_size, GFP_KERNEL);
>   	if (!data)
> @@ -967,7 +967,7 @@ static ssize_t dp_dpcd_data_read(struct file *f, char __user *buf,
>   	struct dc_link *link = connector->dc_link;
>   	uint32_t read_size = connector->debugfs_dpcd_size;
>   
> -	if (size < read_size)
> +	if (!read_size || size < read_size)
>   		return 0;
>   
>   	data = kzalloc(read_size, GFP_KERNEL);
>