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Message-ID: <9cdc844a-ba39-4215-b21e-1e1629edc549@gmx.de>
Date: Tue, 27 Feb 2024 14:41:19 +0100
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Subject: Re: [PATCH v2 2/3] platform/x86/amd/pmf: Do not use readl() for
 policy buffer access
To: =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Cc: Shyam-sundar.S-k@amd.com,
 Mika Westerberg <mika.westerberg@linux.intel.com>,
 sathyanarayanan.kuppuswamy@linux.intel.com,
 Hans de Goede <hdegoede@redhat.com>, platform-driver-x86@vger.kernel.org,
 LKML <linux-kernel@vger.kernel.org>
References: <20240223163901.13504-1-W_Armin@gmx.de>
 <20240223163901.13504-2-W_Armin@gmx.de>
 <e2b81849-3435-3efb-f2da-b74ac7f99a50@linux.intel.com>
Content-Language: en-US
From: Armin Wolf <W_Armin@gmx.de>
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Am 27.02.24 um 13:59 schrieb Ilpo J=C3=A4rvinen:

> On Fri, 23 Feb 2024, Armin Wolf wrote:
>
>> The policy buffer is allocated using normal memory allocation
>> functions, so readl() should not be used on it.
>>
>> Use get_unaligned_le32() instead.
>>
>> Compile-tested only.
>>
>> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
>> ---
>>   drivers/platform/x86/amd/pmf/tee-if.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/platform/x86/amd/pmf/tee-if.c b/drivers/platform/x=
86/amd/pmf/tee-if.c
>> index 16973bebf55f..3220b6580270 100644
>> --- a/drivers/platform/x86/amd/pmf/tee-if.c
>> +++ b/drivers/platform/x86/amd/pmf/tee-if.c
>> @@ -11,6 +11,7 @@
>>   #include <linux/debugfs.h>
>>   #include <linux/tee_drv.h>
>>   #include <linux/uuid.h>
>> +#include <asm/unaligned.h>
>>   #include "pmf.h"
>>
>>   #define MAX_TEE_PARAM	4
>> @@ -249,8 +250,8 @@ static int amd_pmf_start_policy_engine(struct amd_p=
mf_dev *dev)
>>   	u32 cookie, length;
>>   	int res;
>>
>> -	cookie =3D readl(dev->policy_buf + POLICY_COOKIE_OFFSET);
>> -	length =3D readl(dev->policy_buf + POLICY_COOKIE_LEN);
>> +	cookie =3D get_unaligned_le32(dev->policy_buf + POLICY_COOKIE_OFFSET)=
;
>> +	length =3D get_unaligned_le32(dev->policy_buf + POLICY_COOKIE_LEN);
> I don't understand you need _unaligned_ here, the offsets should be dwor=
d
> aligned, no?
>
> #define POLICY_COOKIE_OFFSET      0x10
> #define POLICY_COOKIE_LEN         0x14
>
Hi,

you are right about this.

However i just noticed that the driver does not validate that the policy b=
uffer is big enough
before accessing the data.

I will prepare a separate patch series to address this.

Thanks,
Armin Wolf