Messages in this thread | | | Date | Tue, 14 Jul 2020 14:32:18 +0300 | From | Jarkko Sakkinen <> | Subject | Re: [PATCH] tpm: avoid accessing cleared ops during shutdown |
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On Fri, Jul 10, 2020 at 11:25:44AM -0700, Andrey Pronin wrote: > > Why does not tpm_del_char_device need this? > > "Not" is a typo in the sentence above, right? tpm_del_char_device *does* > need the fix. When tpm_class_shutdown is called it sets chip->ops to > NULL. If tpm_del_char_device is called after that, it doesn't check if > chip->ops is NULL (normal kernel API and char device API calls go > through tpm_try_get_ops, but tpm_del_char_device doesn't) and proceeds to > call tpm2_shutdown(), which tries sending the command and dereferences > chip->ops.
It's a typo, yes. Sorry about that.
tpm_class_shutdown() is essentially tail of tpm_del_char_device().
To clean things up, I'd suggest dropping tpm_del_char_device() and call tpm_class_shutdown() in tpm_chip_unregisters() along, and open coding things that prepend it in tpm_del_char_device().
/Jarkko
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