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?
