Messages in this thread | | | Date | Thu, 6 Jun 2019 15:28:42 +0200 | From | Greg KH <> | Subject | Re: [PATCH V4 04/12] misc: xilinx_sdfec: Add open, close and ioctl |
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On Sat, May 25, 2019 at 12:37:17PM +0100, Dragan Cvetic wrote: > +static int xsdfec_dev_open(struct inode *iptr, struct file *fptr) > +{ > + return 0; > +} > + > +static int xsdfec_dev_release(struct inode *iptr, struct file *fptr) > +{ > + return 0; > +}
empty open/close functions are never needed, just drop them.
> + > +static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd, > + unsigned long data) > +{ > + struct xsdfec_dev *xsdfec; > + void __user *arg = NULL; > + int rval = -EINVAL; > + > + xsdfec = container_of(fptr->private_data, struct xsdfec_dev, miscdev); > + if (!xsdfec) > + return rval;
It is impossible for container_of() to return NULL, unless something very magical and rare just happened. It's just doing pointer math, you can never check the return value of it.
> + > + if (_IOC_TYPE(cmd) != XSDFEC_MAGIC) > + return -ENOTTY;
How can this happen?
> + > + /* check if ioctl argument is present and valid */ > + if (_IOC_DIR(cmd) != _IOC_NONE) { > + arg = (void __user *)data; > + if (!arg) > + return rval; > + } > + > + switch (cmd) { > + default: > + /* Should not get here */ > + dev_warn(xsdfec->dev, "Undefined SDFEC IOCTL");
Nice that userspace has a way to fill up the kernel log :(
Just return the correct error here, don't log it.
thanks,
greg k-h
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