linux-kernel - Re: [PATCH v2] acer-wmi: fix memory leaks in wmab

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Date:	Tue, 13 Jul 2010 09:03:55 +0800
From:	Axel Lin <axel.lin@...il.com>
To:	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	Carlos Corbacho <carlos@...angeworlds.co.uk>,
	Matthew Garrett <mjg@...hat.com>,
	Thomas Renninger <trenn@...e.de>,
	Alan Jenkins <alan-jenkins@...fmail.co.uk>,
	platform-driver-x86@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v2] acer-wmi: fix memory leaks in wmab_execute error
	path

hi Andrew,
I just found acer-wmi-fix-memory-leaks-in-wmab_execute-error-path.patch added to -mm tree.
But I think the V2 version is the correct one.
If the second wmab_execute fail (for any reason) , we need to free the existing buffer before return status.
Sould I resend the patch?


Regards,
Axel

於 五，2010-07-09 於 12:37 +0800，Axel Lin 提到：
> When acpi_evaluate_object() is passed ACPI_ALLOCATE_BUFFER,
> the caller must kfree the returned buffer if AE_OK is returned.
> 
> Call Trace:
> wmab_execute
>   -> wmi_evaluate_method
>     -> acpi_evaluate_object
> 
> Thus if callers of wmab_execute() pass ACPI_ALLOCATE_BUFFER,
> the return buffer must be kfreed if wmab_execute return AE_OK.
> 
> Signed-off-by: Axel Lin <axel.lin@...il.com>
> ---
>  drivers/platform/x86/acer-wmi.c |   11 ++++++++++-
>  1 files changed, 10 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
> index 1ea6c43..3f44446 100644
> --- a/drivers/platform/x86/acer-wmi.c
> +++ b/drivers/platform/x86/acer-wmi.c
> @@ -555,6 +555,7 @@ static acpi_status AMW0_find_mailled(void)
>  	obj->buffer.length == sizeof(struct wmab_ret)) {
>  		ret = *((struct wmab_ret *) obj->buffer.pointer);
>  	} else {
> +		kfree(out.pointer);
>  		return AE_ERROR;
>  	}
>  
> @@ -598,6 +599,7 @@ static acpi_status AMW0_set_capabilities(void)
>  	obj->buffer.length == sizeof(struct wmab_ret)) {
>  		ret = *((struct wmab_ret *) obj->buffer.pointer);
>  	} else {
> +		kfree(out.pointer);
>  		return AE_ERROR;
>  	}
>  
> @@ -607,15 +609,22 @@ static acpi_status AMW0_set_capabilities(void)
>  	args.ebx = 2 << 8;
>  	args.ebx |= ACER_AMW0_BLUETOOTH_MASK;
>  
> +	/*
> +	 * It's ok to use existing buffer for next wmab_execute call.
> +	 * But we need to kfree(out.pointer) if next wmab_execute fail.
> +	 */
>  	status = wmab_execute(&args, &out);
> -	if (ACPI_FAILURE(status))
> +	if (ACPI_FAILURE(status)) {
> +		kfree(out.pointer);
>  		return status;
> +	}
>  
>  	obj = (union acpi_object *) out.pointer;
>  	if (obj && obj->type == ACPI_TYPE_BUFFER
>  	&& obj->buffer.length == sizeof(struct wmab_ret)) {
>  		ret = *((struct wmab_ret *) obj->buffer.pointer);
>  	} else {
> +		kfree(out.pointer);
>  		return AE_ERROR;
>  	}
>  

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