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From:   Jani Nikula <jani.nikula@linux.intel.com>
To:     Xia Fukun <xiafukun@huawei.com>, airlied@gmail.com,
        daniel@ffwll.ch, ville.syrjala@linux.intel.com,
        lucas.demarchi@intel.com, joonas.lahtinen@linux.intel.com
Cc:     rodrigo.vivi@intel.com, tvrtko.ursulin@linux.intel.com,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, xiafukun@huawei.com
Subject: Re: [PATCH] drm/i915/bios: fix a memory leak in generate_lfp_data_ptrs
In-Reply-To: <20221125063428.69486-1-xiafukun@huawei.com>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
References: <20221125063428.69486-1-xiafukun@huawei.com>
Date:   Fri, 25 Nov 2022 10:18:18 +0200
Message-ID: <875yf35tx1.fsf@intel.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Fri, 25 Nov 2022, Xia Fukun <xiafukun@huawei.com> wrote:
> When (size != 0 || ptrs->lvds_ entries != 3), the program tries to
> free() the ptrs. However, the ptrs is not created by calling kzmalloc(),
> but is obtained by pointer offset operation.
> This may lead to memory leaks or undefined behavior.

Yeah probably worse things will happen than just leak.

>
> Fix this by replacing the arguments of kfree() with ptrs_block.
>
> Fixes: a87d0a847607 ("drm/i915/bios: Generate LFP data table pointers if the VBT lacks them")
> Signed-off-by: Xia Fukun <xiafukun@huawei.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_bios.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 28bdb936cd1f..edbdb949b6ce 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -414,7 +414,7 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
>  		ptrs->lvds_entries++;
>  
>  	if (size != 0 || ptrs->lvds_entries != 3) {
> -		kfree(ptrs);
> +		kfree(ptrs_block);
>  		return NULL;
>  	}

-- 
Jani Nikula, Intel Open Source Graphics Center