linux-kernel - Re: [PATCH] staging: gasket: Check the return value of gasket_get_bar

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Date:   Mon, 4 May 2020 13:49:33 -0400
From:   Richard Yeh <rcy@...gle.com>
To:     Oscar Carter <oscar.carter@....com>
Cc:     Rob Springer <rspringer@...gle.com>,
        Todd Poynor <toddpoynor@...gle.com>,
        Ben Chan <benchan@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Simon Que <sque@...omium.org>,
        John Joseph <jnjoseph@...gle.com>, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: gasket: Check the return value of
 gasket_get_bar_index()

On Fri, May 01, 2020 at 05:51:18PM +0200, Oscar Carter wrote:
> Check the return value of gasket_get_bar_index function as it can return
> a negative one (-EINVAL). If this happens, a negative index is used in
> the "gasket_dev->bar_data" array.
> 
> Addresses-Coverity-ID: 1438542 ("Negative array index read")
> Fixes: 9a69f5087ccc2 ("drivers/staging: Gasket driver framework + Apex driver")
> Signed-off-by: Oscar Carter <oscar.carter@....com>
> ---
>  drivers/staging/gasket/gasket_core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/staging/gasket/gasket_core.c b/drivers/staging/gasket/gasket_core.c
> index 8e0575fcb4c8..67325fbaf760 100644
> --- a/drivers/staging/gasket/gasket_core.c
> +++ b/drivers/staging/gasket/gasket_core.c
> @@ -925,6 +925,10 @@ do_map_region(const struct gasket_dev *gasket_dev, struct vm_area_struct *vma,
>  		gasket_get_bar_index(gasket_dev,
>  				     (vma->vm_pgoff << PAGE_SHIFT) +
>  				     driver_desc->legacy_mmap_address_offset);
> +
> +	if (bar_index < 0)
> +		return DO_MAP_REGION_INVALID;
> +
>  	phys_base = gasket_dev->bar_data[bar_index].phys_base + phys_offset;
>  	while (mapped_bytes < map_length) {
>  		/*
> --
> 2.20.1
> 

Reviewed-by: Richard Yeh <rcy@...gle.com>