Messages in this thread | | | Date | Mon, 15 Oct 2018 13:41:56 +0300 | From | Jarkko Sakkinen <> | Subject | Re: [PATCH] tpm: fix unused-value issues in tpm_try_transmit |
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On Thu, Oct 11, 2018 at 01:27:58PM +0000, Winkler, Tomas wrote: > > > > On Wed, Oct 10, 2018 at 08:06:38AM -0600, Jason Gunthorpe wrote: > > > On Wed, Oct 10, 2018 at 03:38:17PM +0200, Gustavo A. R. Silva wrote: > > > > Currently, there are some values assigned to variable *rc*, which > > > > are never actually used in any computation, because such variable is > > > > updated at line 550, before they can be used: > > > > > > > > 549out: > > > > 550 rc = tpm_go_idle(chip, flags); > > > > 551 if (rc) > > > > 552 goto out; > > > > > > > > Fix this by removing such assignments. > > > > > > Should this be done by not quashing rc during the error unwind rather > > > than dropping the errors? > > > > Yeah.` > > > > Wondering if tpm_go_idle() should simply be a void-function i.e. issue just a > > warning inside (disclaimer: did not revisit its code when writing this). > > We did have rather a long discussion about it when it was merged. > There are two flows that may crash > rc = tpm2_commit_space() > > but you still can need to > > rc = go_idle() > > which also may crash which may override the previous value. > > Frankly the second one is fatal, the stack will go out of sync. > We may do void here as the stack will crash in a subsequent command. > > The 'goto out' is quite a bug, probably caused by code movement.
I just looked at the code properly and noticed that there is a regression caused by 627448e85c76 ("tpm: separate cmd_ready/go_idle from runtime_pm") i.e. when tpm_go_idle() fails it loops back and retries tpm_go_idle().
/Jarkko
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