2021-10-21 12:21:14

by Amir Mizinski

[permalink] [raw]
Subject: [PATCH v16 2/6] tpm: tpm_tis: Rewrite "tpm_tis_req_canceled()"

From: Amir Mizinski <[email protected]>

tpm_tis_req_canceled() function is used to check if the caller requested
to abort the current operation. It was found that in some cases
tpm_tis_req_canceled() wrongly returned true.
Since a cancel request sets the TPM_STS.commandReady field to TRUE, the
tpm_tis_req_canceled() function should check only the TPM_STS.commandReady
field value.
The case for TPM_VID_WINBOND is wrong and was therefore removed.

Also, the default comparison is wrong. Only cmdReady bit needs to be
compared instead of the full lower status register byte.

Fixes: 1f866057291f (tpm: Fix cancellation of TPM commands (polling mode))
Signed-off-by: Amir Mizinski <[email protected]>
---
drivers/char/tpm/tpm_tis_core.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 0985184..3e60072 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -650,13 +650,11 @@ static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);

switch (priv->manufacturer_id) {
- case TPM_VID_WINBOND:
- return ((status == TPM_STS_VALID) ||
- (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY)));
case TPM_VID_STM:
return (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY));
default:
- return (status == TPM_STS_COMMAND_READY);
+ return ((status & TPM_STS_COMMAND_READY) ==
+ TPM_STS_COMMAND_READY);
}
}

--
2.7.4


2021-10-23 00:48:31

by Jarkko Sakkinen

[permalink] [raw]
Subject: Re: [PATCH v16 2/6] tpm: tpm_tis: Rewrite "tpm_tis_req_canceled()"

On Thu, 2021-10-21 at 15:05 +0300, [email protected] wrote:
> From: Amir Mizinski <[email protected]>
>
> tpm_tis_req_canceled() function is used to check if the caller requested
> to abort the current operation. It was found that in some cases
> tpm_tis_req_canceled() wrongly returned true.
> Since a cancel request sets the TPM_STS.commandReady field to TRUE, the
> tpm_tis_req_canceled() function should check only the TPM_STS.commandReady
> field value.
> The case for TPM_VID_WINBOND is wrong and was therefore removed.
>
> Also, the default comparison is wrong. Only cmdReady bit needs to be
> compared instead of the full lower status register byte.
>
> Fixes: 1f866057291f (tpm: Fix cancellation of TPM commands (polling mode))

Please go through the comments for 1/6 and fix the commit
for the rest of the patches.

/Jarkko