Re: [PATCH v8 07/12] KEYS: trusted: Remove dead branch from tpm2_unseal_cmd

[Jonathan McDowell]

On Tue, Dec 16, 2025 at 11:21:41AM +0200, Jarkko Sakkinen wrote:
> TPM2_Unseal requires TPM2_ST_SESSIONS, and tpm2_unseal_cmd() always does
> set up either password or HMAC session.
>
> Remove the branch in tpm2_unseal_cmd() conditionally setting
> TPM2_ST_NO_SESSIONS. It is faulty but luckily it is never exercised at
> run-time, and thus does not cause regressions.

Reviewed-by: Jonathan McDowell <noodles@xxxxxxxx>

> Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> ---
> security/keys/trusted-keys/trusted_tpm2.c | 10 +---------
> 1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
> index d3a5c5f2b926..3666e3e48eab 100644
> --- a/security/keys/trusted-keys/trusted_tpm2.c
> +++ b/security/keys/trusted-keys/trusted_tpm2.c
> @@ -451,10 +451,8 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
> 			   struct trusted_key_options *options,
> 			   u32 blob_handle)
> {
> -	struct tpm_header *head;
> 	struct tpm_buf buf;
> 	u16 data_len;
> -	int offset;
> 	u8 *data;
> 	int rc;
>
> @@ -495,14 +493,8 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
> 		tpm_buf_append_u16(&buf, options->blobauth_len);
> 		tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
>
> -		if (tpm2_chip_auth(chip)) {
> +		if (tpm2_chip_auth(chip))
> 			tpm_buf_append_hmac_session(chip, &buf, TPM2_SA_ENCRYPT, NULL, 0);
> -		} else  {
> -			offset = buf.handles * 4 + TPM_HEADER_SIZE;
> -			head = (struct tpm_header *)buf.data;
> -			if (tpm_buf_length(&buf) == offset)
> -				head->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
> -		}
> 	}
>
> 	rc = tpm_buf_fill_hmac_session(chip, &buf);
> --
> 2.39.5

J.

--
"Never test for an error condition you don't know how to handle."
 --Steinbach