linux-kernel - Re: Regression from efi: call get_event

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Date:   Fri, 9 Mar 2018 16:54:42 +0000
From:   Jeremy Cline <jeremy@...ine.org>
To:     Thiebaud Weksteen <tweek@...gle.com>
Cc:     hdegoede@...hat.com, Javier Martinez Canillas <javierm@...hat.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: Regression from efi: call get_event_log before ExitBootServices

On Fri, Mar 09, 2018 at 10:43:50AM +0000, Thiebaud Weksteen wrote:
> Thanks a lot for trying out the patch!
> 
> Please don't modify your install at this stage, I think we are hitting a
> firmware bug and that would be awesome if we can fix how we are handling it.
> So, if we reach that stage in the function it could either be that:
> * The allocation did not succeed, somehow, but the firmware still returned
> EFI_SUCCEED.
> * The size requested is incorrect (I'm thinking something like a 1G of
> log). This would be due to either a miscalculation of log_size (possible)
> or; the returned values of GetEventLog are not correct.
> I'm sending a patch to add checks for these. Could you please apply and
> retest?
> Again, thanks for helping debugging this.

No problem, thanks for the help :)

With the new patch:

Locating the TCG2Protocol
Calling GetEventLog on TCG2Protocol
Log returned
log_location is not empty
log_size != 0
log_size < 1M
Allocating memory for storing the logs
Returned from memory allocation
Copying log to new location

And then it hangs. I added a couple more print statements:

diff --git a/drivers/firmware/efi/libstub/tpm.c b/drivers/firmware/efi/libstub/tpm.c
index ee3fac109078..1ab5638bc50e 100644
--- a/drivers/firmware/efi/libstub/tpm.c
+++ b/drivers/firmware/efi/libstub/tpm.c
@@ -148,8 +148,11 @@ void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
        efi_printk(sys_table_arg, "Copying log to new location\n");
 
        memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
+       efi_printk(sys_table_arg, "Successfully memset log_tbl to 0\n");
        log_tbl->size = log_size;
+       efi_printk(sys_table_arg, "Set log_tbl->size\n");
        log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
+       efi_printk(sys_table_arg, "Set log_tbl-version\n");
        memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
 
        efi_printk(sys_table_arg, "Installing the log into the configuration table\n");

and it's hanging at "memset(log_tbl, 0, sizeof(*log_tbl) + log_size);"

Regards,
Jeremy