Messages in this thread | | | Date | Wed, 1 Jun 2011 15:54:30 -0500 | From | Scott Wood <> | Subject | Re: [PATCH 7/7] [v2] drivers/misc: introduce Freescale hypervisor management driver |
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On Wed, 1 Jun 2011 20:46:18 +0100 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> > +static char *strdup_from_user(const char __user *ustr, size_t max) > > +{ > > + size_t len; > > + char *str; > > + > > + len = strnlen_user(ustr, max); > > + if (len > max) > > + return ERR_PTR(-ENAMETOOLONG);
if (len >= max)
> > + str = kmalloc(len, GFP_KERNEL); > > + if (!str) > > + return ERR_PTR(-ENOMEM); > > + > > + if (copy_from_user(str, ustr, len)) > > + return ERR_PTR(-EFAULT); > > + > > + return str; > > +}
Memory leak on the EFAULT path
If strnlen_user gets an exception, it'll return zero, causing a zero-length kmalloc. Will kmalloc(0, ...) return NULL? If so, a bad user pointer would result in -ENOMEM rather than -EFAULT.
> > + default: > > + pr_debug("fsl-hv: unknown ioctl %u\n", cmd); > > + ret = -ENOIOCTLCMD; > > -ENOTTY > > (-ENOIOCTLCMD is an internal indicator designed so driver layers can say > 'dunno, try the next layer up')
There's a check for -ENOIOCTLCMD in vfs_ioctl() -- though it generates -EINVAL rather than -ENOTTY (why?).
Using -ENOIOCTLCMD consistently would make it easier to refactor a toplevel ioctl handler into a nested one, plus consistency is good in general.
> > + * We use the same interrupt handler for all doorbells. Whenever a doorbell > > + * is rung, and we receive an interrupt, we just put the handle for that > > + * doorbell (passed to us as *data) into all of the queues. > > I wonder if these should be presented as IRQs or whether that makes no > sense ?
They are presented as IRQs. This driver registers the same handler for all doorbell IRQs, and pipes the notifications up to userspace, but you could also directly register a kernel handler for an individual doorbell IRQ.
> > +static irqreturn_t fsl_hv_shutdown_isr(int irq, void *data) > > +{ > > + schedule_work(&power_off); > > + > > + /* We should never get here */ > > Probably worth printing something if you do (panic(...) ?)
I don't think the comment is accurate. We've just scheduled the workqueue, not waited for it to complete.
Timur, shouldn't this schedule orderly_poweroff rather than kernel_power_off?
-Scott
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