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From: Hans de Goede <hdegoede@redhat.com>
To: Mario Limonciello <mario.limonciello@dell.com>,
	Mark Gross <mgross@linux.intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>, platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH] platform/x86: dell-wmi-sysman: fix a NULL pointer dereference
Date: Sat, 30 Jan 2021 22:43:42 +0100
Message-ID: <0da9ca30-53b1-8d34-4fc7-62edb6423b26@redhat.com> (raw)
In-Reply-To: <20210129172654.2326751-1-mario.limonciello@dell.com>

Hi,

On 1/29/21 6:26 PM, Mario Limonciello wrote:
> An upcoming Dell platform is causing a NULL pointer dereference
> in dell-wmi-sysman initialization.  Validate that the input from
> BIOS matches correct ACPI types and abort module initialization
> if it fails.
> 
> This leads to a memory leak that needs to be cleaned up properly.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
> ---
>  drivers/platform/x86/dell-wmi-sysman/sysman.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/dell-wmi-sysman/sysman.c b/drivers/platform/x86/dell-wmi-sysman/sysman.c
> index dc6dd531c996..38b497991071 100644
> --- a/drivers/platform/x86/dell-wmi-sysman/sysman.c
> +++ b/drivers/platform/x86/dell-wmi-sysman/sysman.c
> @@ -419,13 +419,19 @@ static int init_bios_attributes(int attr_type, const char *guid)
>  		return retval;
>  	/* need to use specific instance_id and guid combination to get right data */
>  	obj = get_wmiobj_pointer(instance_id, guid);
> -	if (!obj)
> +	if (!obj || obj->type != ACPI_TYPE_PACKAGE) {
> +		release_attributes_data();

All calls of  init_bios_attributes() have the following error handling:

        ret = init_bios_attributes(INT, DELL_WMI_BIOS_INTEGER_ATTRIBUTE_GUID);
        if (ret) {
                pr_debug("failed to populate integer type attributes\n");
                goto fail_create_group;
        }

	...

fail_create_group:
        release_attributes_data();

So that added release_attributes_data() call is not necessary. If you can respin
this patch Monday with the release_attributes_data(); addition dropped, then
I will try to get this to Linus in time for 5.11 .

Or I can fix this up locally if you agree with dropping the unnecessary
release_attributes_data() call.

Regards,

Hans




>  		return -ENODEV;
> +	}
>  	elements = obj->package.elements;
>  
>  	mutex_lock(&wmi_priv.mutex);
>  	while (elements) {
>  		/* sanity checking */
> +		if (elements[ATTR_NAME].type != ACPI_TYPE_STRING) {
> +			pr_debug("incorrect element type\n");
> +			goto nextobj;
> +		}
>  		if (strlen(elements[ATTR_NAME].string.pointer) == 0) {
>  			pr_debug("empty attribute found\n");
>  			goto nextobj;
> 


  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-29 17:26 Mario Limonciello
2021-01-29 17:29 ` Limonciello, Mario
2021-01-30  3:55   ` Yuan, Perry
2021-01-30 21:43 ` Hans de Goede [this message]
     [not found]   ` <SA1PR19MB49263EE7ECF0D06962BE00ECFAB79@SA1PR19MB4926.namprd19.prod.outlook.com>
2021-01-31 20:59     ` Hans de Goede
2021-02-01  2:36       ` Perry Yuan
2021-02-01  8:27         ` Hans de Goede

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