linux-kernel - Re: [PATCH] tpm2: fix off-by-one comparison and out-of-bounds read error

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Message-ID: <20170322114256.pdwg6buj2wkhcooy@intel.com>
Date:   Wed, 22 Mar 2017 13:42:56 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        tpmdd-devel@...ts.sourceforge.net, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm2: fix off-by-one comparison and out-of-bounds read
 error

On Mon, Mar 20, 2017 at 02:23:36PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> The comparison of an out of range index into space->context_tbl is
> off-by-one and should be using >= rather than > in the comparison.
> 
> Detected by CoverityScan, CID#1419694 ("Out-of-bounds read")
> 
> Fixes: 849246e7ce9ce ("tpm2: add session handle context saving and restoring to the space code")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/char/tpm/tpm2-space.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
> index d36d81e07076..009934269514 100644
> --- a/drivers/char/tpm/tpm2-space.c
> +++ b/drivers/char/tpm/tpm2-space.c
> @@ -229,7 +229,7 @@ static bool tpm2_map_to_phandle(struct tpm_space *space, void *handle)
>  	int i;
>  
>  	i = 0xFFFFFF - (vhandle & 0xFFFFFF);
> -	if (i > ARRAY_SIZE(space->context_tbl) || !space->context_tbl[i])
> +	if (i >= ARRAY_SIZE(space->context_tbl) || !space->context_tbl[i])
>  		return false;
>  
>  	phandle = space->context_tbl[i];
> -- 
> 2.11.0

Thanks. If you don't mind, I would squash this to that patch?

/Jarkko