On Fri Feb 2, 2024 at 5:08 AM EET, Lino Sanfilippo wrote: > > > On 01.02.24 23:21, Jarkko Sakkinen wrote: > > > > > On Wed Jan 31, 2024 at 7:08 PM EET, Daniel P. Smith wrote: > >> Commit 933bfc5ad213 introduced the use of a locality counter to control > >> when a > >> locality request is allowed to be sent to the TPM. In the commit, the > >> counter > >> is indiscriminately decremented. Thus creating a situation for an integer > >> underflow of the counter. > > > > What is the sequence of events that leads to this triggering the > > underflow? This information should be represent in the commit message. > > > > AFAIU this is: > > 1. We start with a locality_counter of 0 and then we call > tpm_tis_request_locality() > for the first time, but since a locality is (unexpectedly) already active > check_locality() and consequently > __tpm_tis_request_locality() return "true". This prevents the > locality_counter from being increased > to 1, see > > ret = __tpm_tis_request_locality(chip, l); > if (!ret) /* Counter not increased since ret == 1 */ > priv->locality_count++; > > in tpm_tis_request_locality(). > > If now the locality is released the counter is decreased to below zero > (resulting > in an underflow since "locality_counter" is an unsigned int.
Thanks, Daniel, can you transcript this to the commit message? BR, Jarkko
