On Tue, 2020-07-21 at 17:51 -0700, Jerry Snitselaar wrote: > James Bottomley @ 2020-07-21 17:39 MST: > > > 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 > > One other thought, should a note be added above tpm_algorithms to > note that when that is changed TPM_MAX_HASHES should be changed as > well? I certainly can ... it's free. > With the above change to the BUG_ON you can add to v3: OK, I also changed the BUG_ON back to a WARN_ON to match the initial one (if that one ever tripped, we'd get an overflow in the chip- >groups[] as well, so it seems reasonable to keep them matching). James > Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx> >
