On Tue, 2020-07-21 at 17:02 -0700, Jerry Snitselaar wrote: > James Bottomley @ 2020-07-21 16:37 MST: > > > On Tue, 2020-07-21 at 16:16 -0700, Jerry Snitselaar wrote: > > > James Bottomley @ 2020-07-21 08:56 MST: > > > > [...] > > > > + /* > > > > + * This will only trigger if someone has added an > > > > additional > > > > + * hash to the tpm_algorithms enum without > > > > incrementing > > > > + * TPM_MAX_HASHES. This has to be a BUG_ON because > > > > under > > > > this > > > > + * condition, the chip->groups array will overflow > > > > corrupting > > > > + * the chips structure. > > > > + */ > > > > + BUG_ON(chip->groups_cnt > TPM_MAX_HASHES); > > > > > > Should this check be 3 + TPM_MAX_HASHES like below? > > > > No, because at this point only a single additional group has been > > addedin addition to the hashes groups. The first line of > > tpm_sysfs_add_device is > > > > WARN_ON(chip->groups_cnt != 0); > > > > And then we add the unnamed group. This loop over the banks > > follows it, so chip->groups_cnt should be nr_banks_allocated by the > > end (it's the index, which is one fewer than the number of entries > > in chip->groups[]). We have a problem if nr_banks_allocated > > > TPM_MAX_HASHES > > > > which is what the BUG_ON checks. > > > > James > > If the chip supported all 5 listed cases wouldn't groups_cnt be 6 at > this point? Actually, yes, I think it would be because it's pointing at the next free index not the current one. So it should be BUG_ON (chip- >groups_cnt > TPM_MAX_HASHES + 1) James
