linux-kernel - Re: [PATCH] drm/amdgpu: fix out of bounds write

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Message-ID: <8205a660-6990-9007-48c9-453117d16f72@amd.com>
Date:   Wed, 27 Oct 2021 11:22:29 -0400
From:   Harry Wentland <harry.wentland@....com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Thelford Williams <tdwilliamsiv@...il.com>
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, David Airlie <airlied@...ux.ie>,
        Alex Deucher <alexander.deucher@....com>,
        Patrik Jakobsson <patrik.r.jakobsson@...il.com>
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 <tdwilliamsiv@...il.com>
>> Signed-off-by: Alex Deucher <alexander.deucher@....com>
> 
> 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