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authorIan Abbott <abbotti@mev.co.uk>2015-01-30 21:43:33 +0300
committerMark Brown <broonie@kernel.org>2015-02-02 22:57:19 +0300
commit7782a1a94825db5163f376beb8db6148fdf1aef0 (patch)
tree32dc271b00dd3e065ee250b3e01e759ebcf26753 /drivers/spi/spidev.c
parent97bf6af1f928216fd6c5a66e8a57bfa95a659672 (diff)
downloadlinux-7782a1a94825db5163f376beb8db6148fdf1aef0.tar.xz
spi: spidev: Convert buf pointers for 32-bit compat SPI_IOC_MESSAGE(n)
The SPI_IOC_MESSAGE(n) ioctl commands' argument points to an array of n struct spi_ioc_transfer elements. The spidev's compat_ioctl handler just converts this pointer and passes it on to the unlocked_ioctl handler to process it. The tx_buf and rx_buf members of struct spi_ioc_transfer are of type __u64 and hold pointer values. A 32-bit userspace application running in a 64-bit kernel might not have widened the 32-bit pointers correctly for the kernel. The application might have sign-extended the pointer to when the kernel expects it to be zero-extended, or vice versa, leading to an -EFAULT being returned by spidev_message() if the widened pointer is invalid. Handle the SPI_IOC_MESSAGE(n) ioctl commands specially in the compat_ioctl handler, calling new function spidev_compat_ioctl_message() to handle them. This processes them in the same way as the unlocked_ioctl handler except that it uses compat_ptr() to convert the tx_buf and rx_buf members of each struct spi_ioc_transfer element. To save code, factor out part of the unlocked_ioctl handler into a new function spidev_get_ioc_message(). This checks the ioctl command code is a valid SPI_IOC_MESSAGE(n), determines n and copies the array of n struct spi_ioc_transfer elements from userspace into dynamically allocated memory, returning either a pointer to the memory, an ERR_PTR(-err) value, or NULL (for SPI_IOC_MESSAGE(0)). Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi/spidev.c')
-rw-r--r--drivers/spi/spidev.c121
1 files changed, 97 insertions, 24 deletions
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index 6941e04afb8c..d1ccbfed50a3 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -317,6 +317,37 @@ done:
return status;
}
+static struct spi_ioc_transfer *
+spidev_get_ioc_message(unsigned int cmd, struct spi_ioc_transfer __user *u_ioc,
+ unsigned *n_ioc)
+{
+ struct spi_ioc_transfer *ioc;
+ u32 tmp;
+
+ /* Check type, command number and direction */
+ if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC
+ || _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
+ || _IOC_DIR(cmd) != _IOC_WRITE)
+ return ERR_PTR(-ENOTTY);
+
+ tmp = _IOC_SIZE(cmd);
+ if ((tmp % sizeof(struct spi_ioc_transfer)) != 0)
+ return ERR_PTR(-EINVAL);
+ *n_ioc = tmp / sizeof(struct spi_ioc_transfer);
+ if (*n_ioc == 0)
+ return NULL;
+
+ /* copy into scratch area */
+ ioc = kmalloc(tmp, GFP_KERNEL);
+ if (!ioc)
+ return ERR_PTR(-ENOMEM);
+ if (__copy_from_user(ioc, u_ioc, tmp)) {
+ kfree(ioc);
+ return ERR_PTR(-EFAULT);
+ }
+ return ioc;
+}
+
static long
spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
@@ -456,32 +487,15 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
default:
/* segmented and/or full-duplex I/O request */
- if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
- || _IOC_DIR(cmd) != _IOC_WRITE) {
- retval = -ENOTTY;
- break;
- }
-
- tmp = _IOC_SIZE(cmd);
- if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
- retval = -EINVAL;
- break;
- }
- n_ioc = tmp / sizeof(struct spi_ioc_transfer);
- if (n_ioc == 0)
- break;
-
- /* copy into scratch area */
- ioc = kmalloc(tmp, GFP_KERNEL);
- if (!ioc) {
- retval = -ENOMEM;
- break;
- }
- if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
- kfree(ioc);
- retval = -EFAULT;
+ /* Check message and copy into scratch area */
+ ioc = spidev_get_ioc_message(cmd,
+ (struct spi_ioc_transfer __user *)arg, &n_ioc);
+ if (IS_ERR(ioc)) {
+ retval = PTR_ERR(ioc);
break;
}
+ if (!ioc)
+ break; /* n_ioc is also 0 */
/* translate to spi_message, execute */
retval = spidev_message(spidev, ioc, n_ioc);
@@ -496,8 +510,67 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
#ifdef CONFIG_COMPAT
static long
+spidev_compat_ioc_message(struct file *filp, unsigned int cmd,
+ unsigned long arg)
+{
+ struct spi_ioc_transfer __user *u_ioc;
+ int retval = 0;
+ struct spidev_data *spidev;
+ struct spi_device *spi;
+ unsigned n_ioc, n;
+ struct spi_ioc_transfer *ioc;
+
+ u_ioc = (struct spi_ioc_transfer __user *) compat_ptr(arg);
+ if (!access_ok(VERIFY_READ, u_ioc, _IOC_SIZE(cmd)))
+ return -EFAULT;
+
+ /* guard against device removal before, or while,
+ * we issue this ioctl.
+ */
+ spidev = filp->private_data;
+ spin_lock_irq(&spidev->spi_lock);
+ spi = spi_dev_get(spidev->spi);
+ spin_unlock_irq(&spidev->spi_lock);
+
+ if (spi == NULL)
+ return -ESHUTDOWN;
+
+ /* SPI_IOC_MESSAGE needs the buffer locked "normally" */
+ mutex_lock(&spidev->buf_lock);
+
+ /* Check message and copy into scratch area */
+ ioc = spidev_get_ioc_message(cmd, u_ioc, &n_ioc);
+ if (IS_ERR(ioc)) {
+ retval = PTR_ERR(ioc);
+ goto done;
+ }
+ if (!ioc)
+ goto done; /* n_ioc is also 0 */
+
+ /* Convert buffer pointers */
+ for (n = 0; n < n_ioc; n++) {
+ ioc[n].rx_buf = (uintptr_t) compat_ptr(ioc[n].rx_buf);
+ ioc[n].tx_buf = (uintptr_t) compat_ptr(ioc[n].tx_buf);
+ }
+
+ /* translate to spi_message, execute */
+ retval = spidev_message(spidev, ioc, n_ioc);
+ kfree(ioc);
+
+done:
+ mutex_unlock(&spidev->buf_lock);
+ spi_dev_put(spi);
+ return retval;
+}
+
+static long
spidev_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
+ if (_IOC_TYPE(cmd) == SPI_IOC_MAGIC
+ && _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
+ && _IOC_DIR(cmd) == _IOC_WRITE)
+ return spidev_compat_ioc_message(filp, cmd, arg);
+
return spidev_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
}
#else