Re: usbip: vhci extension: modifications to vhci driver
On Wed, Oct 12, 2016 at 05:24:31AM +, fx IWATA NOBUO wrote: > Hello, > > I will send a patch to clear this warning. > > The current behavior is as following: > vdev_to_vhci() is inline of container_of(). > A pointer (struct vhci_hcd *vhci) may be container_of() from NULL for a > while. > If it is container_of() from NULL, it will not be referenced because of > NULL check of source pointer of the container_of(). Are you looking at linux-next? vdev_to_vhci() derefernces "vdev" to get vdev->rhport so this is a bug and not a false positive. Smatch sometimes does have false positives because it thinks foo->array is a dereference when really we're taking the address of the array. I should fix that... But it understands that container_of(NULL) is ok. regards, dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: usbip: vhci extension: modifications to vhci driver
Hello, > vdev_to_vhci() derefernces "vdev" to get vdev->rhport Yes, you are right. Sorry about my misreading. I'm creating the patch and will send later. Thank you for your help, n.iwata // > -Original Message- > From: Dan Carpenter [mailto:dan.carpen...@oracle.com] > Sent: Wednesday, October 12, 2016 5:57 PM > To: fx IWATA NOBUO > Cc: linux-usb@vger.kernel.org > Subject: Re: usbip: vhci extension: modifications to vhci driver > > On Wed, Oct 12, 2016 at 05:24:31AM +, fx IWATA NOBUO wrote: > > Hello, > > > > I will send a patch to clear this warning. > > > > The current behavior is as following: > > vdev_to_vhci() is inline of container_of(). > > A pointer (struct vhci_hcd *vhci) may be container_of() from NULL for > > a while. > > If it is container_of() from NULL, it will not be referenced because > > of NULL check of source pointer of the container_of(). > > Are you looking at linux-next? vdev_to_vhci() derefernces "vdev" to get > vdev->rhport so this is a bug and not a false positive. > > Smatch sometimes does have false positives because it thinks foo->array > is a dereference when really we're taking the address of the array. I should > fix that... But it understands that container_of(NULL) is ok. > > regards, > dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: usbip: vhci extension: modifications to vhci driver
Hello,
I will send a patch to clear this warning.
The current behavior is as following:
vdev_to_vhci() is inline of container_of().
A pointer (struct vhci_hcd *vhci) may be container_of() from NULL for a
while.
If it is container_of() from NULL, it will not be referenced because of
NULL check of source pointer of the container_of().
Thank you,
n.iwata
//
> -Original Message-
> From: Dan Carpenter [mailto:dan.carpen...@oracle.com]
> Sent: Tuesday, October 11, 2016 4:03 PM
> To: fx IWATA NOBUO
> Cc: linux-usb@vger.kernel.org
> Subject: re: usbip: vhci extension: modifications to vhci driver
>
> Hello Nobuo Iwata,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch 0775a9cbc694: "usbip: vhci extension: modifications to vhci
> driver" from Jun 13, 2016, leads to the following Smatch complaint:
>
> drivers/usb/usbip/vhci_hcd.c:466 vhci_tx_urb()
>warn: variable dereferenced before check 'vdev' (see line 463)
>
> drivers/usb/usbip/vhci_hcd.c
>462struct vhci_priv *priv;
>463struct vhci_hcd *vhci = vdev_to_vhci(vdev);
> ^^ Patch adds a
> new dereference inside the vdev_to_vhci() function.
>
>464unsigned long flags;
>465
>466if (!vdev) {
> ^
> Old code assumed "vdev" could be NULL.
>
>467pr_err("could not get virtual device");
>468return;
>
> regards,
> dan carpenter
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re: usbip: vhci extension: modifications to vhci driver
Hello Nobuo Iwata,
This is a semi-automatic email about new static checker warnings.
The patch 0775a9cbc694: "usbip: vhci extension: modifications to vhci
driver" from Jun 13, 2016, leads to the following Smatch complaint:
drivers/usb/usbip/vhci_hcd.c:466 vhci_tx_urb()
warn: variable dereferenced before check 'vdev' (see line 463)
drivers/usb/usbip/vhci_hcd.c
462 struct vhci_priv *priv;
463 struct vhci_hcd *vhci = vdev_to_vhci(vdev);
^^
Patch adds a new dereference inside the vdev_to_vhci() function.
464 unsigned long flags;
465
466 if (!vdev) {
^
Old code assumed "vdev" could be NULL.
467 pr_err("could not get virtual device");
468 return;
regards,
dan carpenter
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