[RESEND] amdkfd: check ret code for ioctls

[Zhu Lingshan]

On 10/31/2024 11:30 PM, Felix Kuehling wrote:
>
> On 2024-10-31 6:50, Zhu Lingshan wrote:
>> The ioctl functions may fail, causing the args unreliable.
>> Therefore, the args should not be copied to user space.
>>
>> The return code provides enough information for
>> error handling in user space.
>>
>> This commit checks the return code of the ioctl functions
>> and handles errors appropriately when they fail.
> I have reviewed and rejected this patch before. My opinion has not changed. The existing code copies the ioctl arg structure back to user mode even in error cases because user mode needs additional information from that structure for some ioctls.
how can the user space program distinguish the "good informational parameters" from the  "bad default legacy parameters"? There can be other user space programs other than thunk.

what if the user space program doing pulling mode, it can pull the args changes because ioctl is usually slower, our code should be robust.

usually the return code provides enough information for the user space programs.

Thanks
Lingshan
>
> Regards,
>   Felix
>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu at amd.com>
>> ---
>>  drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>> index 3e6b4736a7fe..a184ca0023b5 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>> @@ -3327,6 +3327,8 @@ static long kfd_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
>>  	}
>>  
>>  	retcode = func(filep, process, kdata);
>> +	if (retcode)
>> +		goto err_retcode;
>>  
>>  	if (cmd & IOC_OUT)
>>  		if (copy_to_user((void __user *)arg, kdata, usize) != 0)
>> @@ -3340,6 +3342,7 @@ static long kfd_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
>>  	if (kdata != stack_kdata)
>>  		kfree(kdata);
>>  
>> +err_retcode:
>>  	if (retcode)
>>  		dev_dbg(kfd_device, "ioctl cmd (#0x%x), arg 0x%lx, ret = %d\n",
>>  				nr, arg, retcode);