In net2280_free_request():
If _ep is NULL, then ep is NULL and is dereferenced
while trying to produce an error message.
The patch replaces dev_err() with pr_err() which works fine.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: 9ceafcc2b3ad ("usb: gadget: net2280: print error in ep_ops error paths")
Signed-off-by: Valery Zabrovsky <[email protected]>
---
drivers/usb/gadget/udc/net2280.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/udc/net2280.c b/drivers/usb/gadget/udc/net2280.c
index 1b929c519cd7..a027d1323993 100644
--- a/drivers/usb/gadget/udc/net2280.c
+++ b/drivers/usb/gadget/udc/net2280.c
@@ -584,8 +584,7 @@ static void net2280_free_request(struct usb_ep *_ep, struct usb_request *_req)
ep = container_of(_ep, struct net2280_ep, ep);
if (!_ep || !_req) {
- dev_err(&ep->dev->pdev->dev, "%s: Invalid ep=%p or req=%p\n",
- __func__, _ep, _req);
+ pr_err("%s: Invalid ep=%p or req=%p\n", __func__, _ep, _req);
return;
}
--
2.34.1
On Thu, Mar 16, 2023 at 06:53:55PM +0300, Valery Zabrovsky wrote:
> In net2280_free_request():
> If _ep is NULL, then ep is NULL and is dereferenced
> while trying to produce an error message.
How can that ever happen? How did you test and hit this?
> The patch replaces dev_err() with pr_err() which works fine.
That's not a good idea for driver code to use, sorry.
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
As I have said before, your testing framework needs a lot more work.
good luck!
greg k-h
On Thu, Mar 16, 2023 at 05:19:35PM +0100, Greg Kroah-Hartman wrote:
> On Thu, Mar 16, 2023 at 06:53:55PM +0300, Valery Zabrovsky wrote:
> > In net2280_free_request():
> > If _ep is NULL, then ep is NULL and is dereferenced
> > while trying to produce an error message.
>
> How can that ever happen? How did you test and hit this?
>
> > The patch replaces dev_err() with pr_err() which works fine.
>
> That's not a good idea for driver code to use, sorry.
>
> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> As I have said before, your testing framework needs a lot more work.
>
> good luck!
In situations like this, it might be better to remove the check
entirely. If a driver does pass a NULL pointer, it will lead to an
invalid pointer dereference which will certainly cause an oops and might
very well crash the system. That would be a lot more noticeable than an
error message hidden in a kernel log!
Greg, is there any general policy about the need for sanity checks such
as this one? Like, don't put them in whenever a failure would lead
to an immediate fault which would be easy to track down?
Alan Stern
On Thu, Mar 16, 2023 at 02:22:35PM -0400, Alan Stern wrote:
> On Thu, Mar 16, 2023 at 05:19:35PM +0100, Greg Kroah-Hartman wrote:
> > On Thu, Mar 16, 2023 at 06:53:55PM +0300, Valery Zabrovsky wrote:
> > > In net2280_free_request():
> > > If _ep is NULL, then ep is NULL and is dereferenced
> > > while trying to produce an error message.
> >
> > How can that ever happen? How did you test and hit this?
> >
> > > The patch replaces dev_err() with pr_err() which works fine.
> >
> > That's not a good idea for driver code to use, sorry.
> >
> > > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> >
> > As I have said before, your testing framework needs a lot more work.
> >
> > good luck!
>
> In situations like this, it might be better to remove the check
> entirely. If a driver does pass a NULL pointer, it will lead to an
> invalid pointer dereference which will certainly cause an oops and might
> very well crash the system. That would be a lot more noticeable than an
> error message hidden in a kernel log!
>
> Greg, is there any general policy about the need for sanity checks such
> as this one? Like, don't put them in whenever a failure would lead
> to an immediate fault which would be easy to track down?
That's the policy, no need to check if a caller is abusing the code and
will find out instantly. Otherwise we end up checking on every
function, and that way lies madness.
thanks,
greg k-h