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

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Message-ID: <20191008114559.GD25098@kadam>
Date:   Tue, 8 Oct 2019 14:46:37 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Colin King <colin.king@...onical.com>,
        Jerry Snitselaar <jsnitsel@...hat.com>
Cc:     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 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