Messages in this thread Patch in this message | | | From | Hans-Jürgen Koch <> | Subject | Re: Flaws with "UIO: Add the User IO core code" (with patch) | Date | Sat, 28 Apr 2007 20:52:45 +0200 |
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Am Samstag 28 April 2007 01:19 schrieb Alan Cox: > > +static ssize_t uio_read(struct file *filep, char __user *buf, > > + size_t count, loff_t *ppos) > > +{ > > + struct uio_listener *listener = filep->private_data; > > + struct uio_device *idev = listener->dev; > > + DECLARE_WAITQUEUE(wait, current); > > + ssize_t retval; > > + int event_count; > > + > > + if (idev->info->irq == UIO_IRQ_NONE) > > + return -EIO; > > + > > + if (count != sizeof(int)) > > + return -EINVAL; > > AFAIK we don't currently have any platform that runs binaries with > different sizes of "int" but this is a) an unsigned value anyway, and b) > should be a fixed type (eg u32)
I reviewed the code once more and find it OK. There is only one legal value for the parameter "count" of uio_read(), and that's sizeof(int). The data that is actually read is the element "event" of struct uio_device, which is of type atomic_t. The latter has the size of an int.
Unfortunately, the fact that the read count _must_ be sizeof(int) is not mentioned in the documentation. I'll send a patch for that ASAP.
> > Otherwise it looks ok at the momenmt, although there is a real nasty > waiting for anyone who tries to use it. At the point open is possible or > IRQs can be enabled you are safe in the core merged as idev->info is > always valid, but any driver module trying to go back via info->uio_dev > has a NULL pointer for an early IRQ or open event.
This patch should fix it:
Index: linux-2.6.22-rc/drivers/uio/uio.c =================================================================== --- linux-2.6.22-rc.orig/drivers/uio/uio.c 2007-04-28 20:01:02.000000000 +0200 +++ linux-2.6.22-rc/drivers/uio/uio.c 2007-04-28 20:15:00.000000000 +0200 @@ -633,6 +633,8 @@ if (ret) goto err_uio_dev_add_attributes; + info->uio_dev = idev; + if (idev->info->irq >= 0) { ret = request_irq(idev->info->irq, uio_interrupt, idev->info->irq_flags, idev->info->name, idev); @@ -640,7 +642,6 @@ goto err_request_irq; } - info->uio_dev = idev; return 0; err_request_irq:
Thanks for your review, Hans
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