linux-kernel - Re: [PATCH][next] efi/tpm: fix sanity check of unsigned tbl

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Message-ID: <37d9c70e-12e0-f0a1-b3ff-b2aefb39c223@canonical.com>
Date:   Tue, 8 Oct 2019 17:24:45 +0100
From:   Colin Ian King <colin.king@...onical.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Ingo Molnar <mingo@...nel.org>, linux-efi@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] efi/tpm: fix sanity check of unsigned tbl_size
 being less than zero

On 08/10/2019 17:15, Jerry Snitselaar wrote:
> On Tue Oct 08 19, Dan Carpenter wrote:
>> On Tue, Oct 08, 2019 at 11:01:53AM +0100, Colin King wrote:
>>> From: Colin Ian King <colin.king@...onical.com>
>>>
>>> Currently the check for tbl_size being less than zero is always false
>>> because tbl_size is unsigned. Fix this by making it a signed int.
>>>
>>> Addresses-Coverity: ("Unsigned compared against 0")
>>> Fixes: e658c82be556 ("efi/tpm: Only set 'efi_tpm_final_log_size'
>>> after successful event log parsing")
>>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>>> ---
>>>  drivers/firmware/efi/tpm.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
>>> index 703469c1ab8e..ebd7977653a8 100644
>>> --- a/drivers/firmware/efi/tpm.c
>>> +++ b/drivers/firmware/efi/tpm.c
>>> @@ -40,7 +40,7 @@ int __init efi_tpm_eventlog_init(void)
>>>  {
>>>      struct linux_efi_tpm_eventlog *log_tbl;
>>>      struct efi_tcg2_final_events_table *final_tbl;
>>> -    unsigned int tbl_size;
>>> +    int tbl_size;
>>>      int ret = 0;
>>
>>
>> Do we need to do a "ret = tbl_size;"?  Currently we return success.
>> It's a pitty that tpm2_calc_event_log_size() returns a -1 instead of
>> -EINVAL.
>>
>> regards,
>> dan carpenter
>>
> 
> perhaps "ret = -EINVAL;"? Currently nothing checks the return value of
> efi_tpm_eventlog_init though.

I doubt I'll fix that for my current fix as a V2.