2021-10-27 21:27:25

by Guenter Roeck

Subject: Re: [PATCH] drm/amdgpu: fix out of bounds write

On Wed, Oct 13, 2021 at 04:04:13PM -0400, Thelford Williams wrote:
> Size can be any value and is user controlled resulting in overwriting the
> 40 byte array wr_buf with an arbitrary length of data from buf.
>
> Signed-off-by: Thelford Williams <[email protected]>
> Signed-off-by: Alex Deucher <[email protected]>

The fix works, but unless I am missing something it is incomplete.
parse_write_buffer_into_params() is called several times, and the
size parameter is always wrong. This patch only fixes one of several
instances of the problem.

Guenter

> ---
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> 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 814f67d86a3c..9b3ad56607bb 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
> @@ -264,7 +264,7 @@ static ssize_t dp_link_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)) {
> --
> 2.33.0

2021-10-27 21:31:13

by Harry Wentland

Subject: Re: [PATCH] drm/amdgpu: fix out of bounds write

On 2021-10-27 10:39, Guenter Roeck wrote:
> On Wed, Oct 13, 2021 at 04:04:13PM -0400, Thelford Williams wrote:
>> Size can be any value and is user controlled resulting in overwriting the
>> 40 byte array wr_buf with an arbitrary length of data from buf.
>>
>> Signed-off-by: Thelford Williams <[email protected]>
>> Signed-off-by: Alex Deucher <[email protected]>
>
> The fix works, but unless I am missing something it is incomplete.
> parse_write_buffer_into_params() is called several times, and the
> size parameter is always wrong. This patch only fixes one of several
> instances of the problem.
>

Patrik sent a patch that covers all cases:
https://patchwork.freedesktop.org/patch/461554/?series=96341&rev=2

Harry

> Guenter
>
>> ---
>> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> 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 814f67d86a3c..9b3ad56607bb 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
>> @@ -264,7 +264,7 @@ static ssize_t dp_link_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)) {
>> --
>> 2.33.0