Message-ID: <ed39cbe6-0885-a3ab-fc30-7c292e1acc53@datenfreihafen.org>
Date:   Tue, 4 Jan 2022 16:40:41 +0100
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Subject: Re: [PATCH v2] ieee802154: atusb: fix uninit value in
 atusb_set_extended_addr
Content-Language: en-US
To:     Pavel Skripkin <paskripkin@gmail.com>, alex.aring@gmail.com,
        davem@davemloft.net, kuba@kernel.org
Cc:     linux-wpan@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Alexander Potapenko <glider@google.com>
References: <CAB_54W50xKFCWZ5vYuDG2p4ijpd63cSutRrV4MLs9oasLmKgzQ@mail.gmail.com>
 <20220103120925.25207-1-paskripkin@gmail.com>
From:   Stefan Schmidt <stefan@datenfreihafen.org>
In-Reply-To: <20220103120925.25207-1-paskripkin@gmail.com>
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Precedence: bulk

Hello.

On 03.01.22 13:09, Pavel Skripkin wrote:
> Alexander reported a use of uninitialized value in
> atusb_set_extended_addr(), that is caused by reading 0 bytes via
> usb_control_msg().
> 
> Fix it by validating if the number of bytes transferred is actually
> correct, since usb_control_msg() may read less bytes, than was requested
> by caller.
> 
> Fail log:
> 
> BUG: KASAN: uninit-cmp in ieee802154_is_valid_extended_unicast_addr include/linux/ieee802154.h:310 [inline]
> BUG: KASAN: uninit-cmp in atusb_set_extended_addr drivers/net/ieee802154/atusb.c:1000 [inline]
> BUG: KASAN: uninit-cmp in atusb_probe.cold+0x29f/0x14db drivers/net/ieee802154/atusb.c:1056
> Uninit value used in comparison: 311daa649a2003bd stack handle: 000000009a2003bd
>   ieee802154_is_valid_extended_unicast_addr include/linux/ieee802154.h:310 [inline]
>   atusb_set_extended_addr drivers/net/ieee802154/atusb.c:1000 [inline]
>   atusb_probe.cold+0x29f/0x14db drivers/net/ieee802154/atusb.c:1056
>   usb_probe_interface+0x314/0x7f0 drivers/usb/core/driver.c:396
> 
> Fixes: 7490b008d123 ("ieee802154: add support for atusb transceiver")
> Reported-by: Alexander Potapenko <glider@google.com>
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> ---
> 
> Changes in v2:
> 	- Reworked fix approach, since moving to new USB API is not
> 	  suitable for backporting to stable kernels
> 
> ---
>   drivers/net/ieee802154/atusb.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ieee802154/atusb.c b/drivers/net/ieee802154/atusb.c
> index 23ee0b14cbfa..e6cc816dd7a1 100644
> --- a/drivers/net/ieee802154/atusb.c
> +++ b/drivers/net/ieee802154/atusb.c
> @@ -93,7 +93,9 @@ static int atusb_control_msg(struct atusb *atusb, unsigned int pipe,
>   
>   	ret = usb_control_msg(usb_dev, pipe, request, requesttype,
>   			      value, index, data, size, timeout);
> -	if (ret < 0) {
> +	if (ret < size) {
> +		ret = ret < 0 ? ret : -ENODATA;
> +
>   		atusb->err = ret;
>   		dev_err(&usb_dev->dev,
>   			"%s: req 0x%02x val 0x%x idx 0x%x, error %d\n",
> 

It compiles, but does not work on the real hardware.

[    1.114698] usb 1-1: new full-speed USB device number 2 using uhci_hcd
[    1.261691] usb 1-1: New USB device found, idVendor=20b7, 
idProduct=1540, bcdDevice= 0.01
[    1.263421] usb 1-1: New USB device strings: Mfr=0, Product=0, 
SerialNumber=1
[    1.264952] usb 1-1: SerialNumber: 4630333438371502231a
[    1.278042] usb 1-1: ATUSB: AT86RF231 version 2
[    1.281087] usb 1-1: Firmware: major: 0, minor: 3, hardware type: 
ATUSB (2)
[    1.285191] usb 1-1: atusb_control_msg: req 0x01 val 0x0 idx 0x0, 
error -61
[    1.286903] usb 1-1: failed to fetch extended address, random address set
[    1.288757] usb 1-1: atusb_probe: initialization failed, error = -61
[    1.290922] atusb: probe of 1-1:1.0 failed with error -61


Without your patch it works as expected:

[    1.091925] usb 1-1: new full-speed USB device number 2 using uhci_hcd
[    1.237743] usb 1-1: New USB device found, idVendor=20b7, 
idProduct=1540, bcdDevice= 0.01
[    1.239788] usb 1-1: New USB device strings: Mfr=0, Product=0, 
SerialNumber=1
[    1.241432] usb 1-1: SerialNumber: 4630333438371502231a
[    1.255012] usb 1-1: ATUSB: AT86RF231 version 2
[    1.258073] usb 1-1: Firmware: major: 0, minor: 3, hardware type: 
ATUSB (2)
[    1.262170] usb 1-1: Firmware: build #132 Mo 28. Nov 16:20:35 CET 2016
[    1.266195] usb 1-1: Read permanent extended address 
10:e2:d5:ff:ff:00:02:e8 from device

regards
Stefan Schmidt