Re: [PATCH] drm/amdgpu: Fix even more out of bound writes from debugfs

[Harry Wentland <harry.wentland@xxxxxxx>]

On 2021-10-27 09:03, Patrik Jakobsson wrote:
> CVE-2021-42327 was fixed by:
> 
> commit f23750b5b3d98653b31d4469592935ef6364ad67
> Author: Thelford Williams <tdwilliamsiv@xxxxxxxxx>
> Date:   Wed Oct 13 16:04:13 2021 -0400
> 
>     drm/amdgpu: fix out of bounds write
> 
> but amdgpu_dm_debugfs.c contains more of the same issue so fix the
> remaining ones.
> 
> Fixes: 918698d5c2b5 ("drm/amd/display: Return the number of bytes parsed than allocated")
> Signed-off-by: Patrik Jakobsson <pjakobsson@xxxxxxx>
> ---
>  .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c    | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 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 1a68a674913c..33bdf15febc6 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
> @@ -491,7 +491,7 @@ static ssize_t dp_phy_settings_write(struct file *f, const char __user *buf,
>  	if (!wr_buf)
>  		return -ENOSPC;
>  
> -	if (parse_write_buffer_into_params(wr_buf, size,
> +	if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
>  					   (long *)param, buf,
>  					   max_param_num,
>  					   &param_nums)) {
> @@ -643,7 +643,7 @@ static ssize_t dp_phy_test_pattern_debugfs_write(struct file *f, const char __us
>  	if (!wr_buf)
>  		return -ENOSPC;
>  
> -	if (parse_write_buffer_into_params(wr_buf, size,
> +	if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
>  					   (long *)param, buf,
>  					   max_param_num,
>  					   &param_nums)) {
> @@ -918,7 +918,7 @@ static ssize_t dp_dsc_passthrough_set(struct file *f, const char __user *buf,
>  		return -ENOSPC;
>  	}
>  
> -	if (parse_write_buffer_into_params(wr_buf, size,
> +	if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
>  					   &param, buf,
>  					   max_param_num,
>  					   &param_nums)) {
> @@ -1215,7 +1215,7 @@ static ssize_t trigger_hotplug(struct file *f, const char __user *buf,
>  		return -ENOSPC;
>  	}
>  
> -	if (parse_write_buffer_into_params(wr_buf, size,
> +	if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
>  						(long *)param, buf,
>  						max_param_num,
>  						&param_nums)) {
> @@ -1400,7 +1400,7 @@ static ssize_t dp_dsc_clock_en_write(struct file *f, const char __user *buf,
>  		return -ENOSPC;
>  	}
>  
> -	if (parse_write_buffer_into_params(wr_buf, size,
> +	if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
>  					    (long *)param, buf,
>  					    max_param_num,
>  					    &param_nums)) {
> @@ -1585,7 +1585,7 @@ static ssize_t dp_dsc_slice_width_write(struct file *f, const char __user *buf,
>  		return -ENOSPC;
>  	}
>  
> -	if (parse_write_buffer_into_params(wr_buf, size,
> +	if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
>  					    (long *)param, buf,
>  					    max_param_num,
>  					    &param_nums)) {
> @@ -1770,7 +1770,7 @@ static ssize_t dp_dsc_slice_height_write(struct file *f, const char __user *buf,
>  		return -ENOSPC;
>  	}
>  
> -	if (parse_write_buffer_into_params(wr_buf, size,
> +	if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
>  					    (long *)param, buf,
>  					    max_param_num,
>  					    &param_nums)) {
> @@ -1948,7 +1948,7 @@ static ssize_t dp_dsc_bits_per_pixel_write(struct file *f, const char __user *bu
>  		return -ENOSPC;
>  	}
>  
> -	if (parse_write_buffer_into_params(wr_buf, size,
> +	if (parse_write_buffer_into_params(wr_buf, wr_buf_size,
>  					    (long *)param, buf,
>  					    max_param_num,
>  					    &param_nums)) {
> 


Thanks. This looks good but you seem to be missing another
instance of this in dp_max_bpc_write.

We'll also want to Linus's suggestion in [1] but I can post
another patch for that.

https://lkml.org/lkml/2021/10/26/993

Harry