2024-02-18 16:55:00

by Mario Limonciello

Subject: [PATCH] platform/x86/amd/pmf: Fix a potential race with policy binary sideload

The debugfs `update_policy` file is created before
amd_pmf_start_policy_engine() has completed, and thus there could be
a possible (albeit unlikely) race between sideloading a policy and the
BIOS policy getting setup.

Move the debugfs file creation after all BIOS policy is setup.

Fixes: 10817f28e533 ("platform/x86/amd/pmf: Add capability to sideload of policy binary")
Reported-by: Hans de Goede <[email protected]>
Closes: https://lore.kernel.org/platform-driver-x86/[email protected]/T/#m2c445f135e5ef9b53184be7fc9df84e15f89d4d9
Signed-off-by: Mario Limonciello <[email protected]>
---
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 4f74de680654..8527dca9cf56 100644
--- a/drivers/platform/x86/amd/pmf/tee-if.c
+++ b/drivers/platform/x86/amd/pmf/tee-if.c
@@ -456,8 +456,6 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
memcpy(dev->policy_buf, dev->policy_base, dev->policy_sz);

amd_pmf_hex_dump_pb(dev);
- if (pb_side_load)
- amd_pmf_open_pb(dev, dev->dbgfs_dir);

dev->prev_data = kzalloc(sizeof(*dev->prev_data), GFP_KERNEL);
if (!dev->prev_data)
@@ -467,6 +465,9 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
if (ret)
goto error;

+ if (pb_side_load)
+ amd_pmf_open_pb(dev, dev->dbgfs_dir);
+
return 0;

error:
--
2.34.1

2024-02-19 12:54:58

by Hans de Goede

Subject: Re: [PATCH] platform/x86/amd/pmf: Fix a potential race with policy binary sideload

Hi,

On 2/17/24 02:56, Mario Limonciello wrote:
> The debugfs `update_policy` file is created before
> amd_pmf_start_policy_engine() has completed, and thus there could be
> a possible (albeit unlikely) race between sideloading a policy and the
> BIOS policy getting setup.
>
> Move the debugfs file creation after all BIOS policy is setup.
>
> Fixes: 10817f28e533 ("platform/x86/amd/pmf: Add capability to sideload of policy binary")
> Reported-by: Hans de Goede <[email protected]>
> Closes: https://lore.kernel.org/platform-driver-x86/[email protected]/T/#m2c445f135e5ef9b53184be7fc9df84e15f89d4d9
> Signed-off-by: Mario Limonciello <[email protected]>

Thank you for your patch, I've applied this patch to my review-hans
branch:
https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=review-hans

Note it will show up in my review-hans branch once I've pushed my
local branch there, which might take a while.

I will include this patch in my next fixes pull-req to Linus
for the current kernel development cycle.

Regards,

Hans

> ---
> 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 4f74de680654..8527dca9cf56 100644
> --- a/drivers/platform/x86/amd/pmf/tee-if.c
> +++ b/drivers/platform/x86/amd/pmf/tee-if.c
> @@ -456,8 +456,6 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
> memcpy(dev->policy_buf, dev->policy_base, dev->policy_sz);
>
> amd_pmf_hex_dump_pb(dev);
> - if (pb_side_load)
> - amd_pmf_open_pb(dev, dev->dbgfs_dir);
>
> dev->prev_data = kzalloc(sizeof(*dev->prev_data), GFP_KERNEL);
> if (!dev->prev_data)
> @@ -467,6 +465,9 @@ int amd_pmf_init_smart_pc(struct amd_pmf_dev *dev)
> if (ret)
> goto error;
>
> + if (pb_side_load)
> + amd_pmf_open_pb(dev, dev->dbgfs_dir);
> +
> return 0;
>
> error: