Patchwork cdc-phonet: Don't leak in usbpn_open

login
register
mail settings
Submitter Jesper Juhl
Date Aug. 7, 2012, 9:56 p.m.
Message ID <alpine.LNX.2.00.1208072354030.3227@swampdragon.chaosbits.net>
Download mbox | patch
Permalink /patch/175809/
State Accepted
Delegated to: David Miller
Headers show

Comments

Jesper Juhl - Aug. 7, 2012, 9:56 p.m.
We allocate memory for 'req' with usb_alloc_urb() and then test
'if (!req || rx_submit(pnd, req, GFP_KERNEL | __GFP_COLD))'.
If we enter that branch due to '!req' then there is no problem. But if
we enter the branch due to 'req' being != 0 and the 'rx_submit()' call
being false, then we'll leak the memory we allocated.
Deal with the leak by always calling 'usb_free_urb(req)' when entering
the branch. If 'req' happens to be 0 then the call is harmless, if it
is not 0 then we free the memory we allocated but don't need.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
---
 drivers/net/usb/cdc-phonet.c | 1 +
 1 file changed, 1 insertion(+)

  Only compile tested due to lack of hardware.
Rémi Denis-Courmont - Aug. 8, 2012, 7:12 a.m.
Le mercredi 8 août 2012 00:56:26 Jesper Juhl, vous avez écrit :
> We allocate memory for 'req' with usb_alloc_urb() and then test
> 'if (!req || rx_submit(pnd, req, GFP_KERNEL | __GFP_COLD))'.
> If we enter that branch due to '!req' then there is no problem. But if
> we enter the branch due to 'req' being != 0 and the 'rx_submit()' call
> being false, then we'll leak the memory we allocated.
> Deal with the leak by always calling 'usb_free_urb(req)' when entering
> the branch. If 'req' happens to be 0 then the call is harmless, if it
> is not 0 then we free the memory we allocated but don't need.
>
> Signed-off-by: Jesper Juhl <jj@chaosbits.net>

Acked-by: Rémi Denis-Courmont <remi@remlab.net>

> ---
>  drivers/net/usb/cdc-phonet.c | 1 +
>  1 file changed, 1 insertion(+)
> 
>   Only compile tested due to lack of hardware.

Hardware won't help you much with testing the error case anyway.
David Miller - Aug. 8, 2012, 11:05 p.m.
From: "Rémi Denis-Courmont" <remi@remlab.net>
Date: Wed, 8 Aug 2012 10:12:06 +0300

> Le mercredi 8 août 2012 00:56:26 Jesper Juhl, vous avez écrit :
>> We allocate memory for 'req' with usb_alloc_urb() and then test
>> 'if (!req || rx_submit(pnd, req, GFP_KERNEL | __GFP_COLD))'.
>> If we enter that branch due to '!req' then there is no problem. But if
>> we enter the branch due to 'req' being != 0 and the 'rx_submit()' call
>> being false, then we'll leak the memory we allocated.
>> Deal with the leak by always calling 'usb_free_urb(req)' when entering
>> the branch. If 'req' happens to be 0 then the call is harmless, if it
>> is not 0 then we free the memory we allocated but don't need.
>>
>> Signed-off-by: Jesper Juhl <jj@chaosbits.net>
> 
> Acked-by: Rémi Denis-Courmont <remi@remlab.net>

Applied.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/drivers/net/usb/cdc-phonet.c b/drivers/net/usb/cdc-phonet.c
index 6461004..7d78669 100644
--- a/drivers/net/usb/cdc-phonet.c
+++ b/drivers/net/usb/cdc-phonet.c
@@ -232,6 +232,7 @@  static int usbpn_open(struct net_device *dev)
 		struct urb *req = usb_alloc_urb(0, GFP_KERNEL);
 
 		if (!req || rx_submit(pnd, req, GFP_KERNEL | __GFP_COLD)) {
+			usb_free_urb(req);
 			usbpn_close(dev);
 			return -ENOMEM;
 		}