Re: [PATCH] tpm: fix tpm disabling if NULL name changes

[Jarkko Sakkinen <jarkko@kernel.org>]

On Fri, Mar 13, 2026 at 10:31:03AM -0400, James Bottomley wrote:
> There's a logic error in the earlier fix which means that if the NULL
> name comparison fails, the tpm isn't disabled because rc remains zero.
> Fix this by setting it to an error.
> 
> Cc: stable@vger.kernel.org # 6.12
> Fixes: cc7d8594342a ("tpm: Rollback tpm2_load_null()")
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> ---
> 
> I didn't actually discover this problem until I was trying to do a
> reset attack demo with an updated kernel.
> 
>  drivers/char/tpm/tpm2-sessions.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-
> sessions.c
> index 3b1cf1ca0420..bd1c0456e775 100644
> --- a/drivers/char/tpm/tpm2-sessions.c
> +++ b/drivers/char/tpm/tpm2-sessions.c
> @@ -961,6 +961,7 @@ static int tpm2_load_null(struct tpm_chip *chip,
> u32 *null_key)
>  	/* Deduce from the name change TPM interference: */
>  	dev_err(&chip->dev, "null key integrity check failed\n");
>  	tpm2_flush_context(chip, tmp_null_key);
> +	rc = -ENODEV;
>  
>  err:
>  	if (rc) {
> -- 
> 2.51.0
> 
> 

Possible to resend (fake ancestor)?

Other than that,

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko