Re: [PATCH v2 2/3] platform/x86/amd/pmf: Do not use readl() for policy buffer access

[Armin Wolf]

Am 27.02.24 um 13:59 schrieb Ilpo Järvinen:

> 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@xxxxxx>
> > ---
> >   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/x86/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_pmf_dev *dev)
> >   	u32 cookie, length;
> >   	int res;
> >
> > -	cookie = readl(dev->policy_buf + POLICY_COOKIE_OFFSET);
> > -	length = readl(dev->policy_buf + POLICY_COOKIE_LEN);
> > +	cookie = get_unaligned_le32(dev->policy_buf + POLICY_COOKIE_OFFSET);
> > +	length = get_unaligned_le32(dev->policy_buf + POLICY_COOKIE_LEN);
> I don't understand you need _unaligned_ here, the offsets should be dword
> 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 buffer is big enough
before accessing the data.

I will prepare a separate patch series to address this.

Thanks,
Armin Wolf