Unverified Commit 833026ad authored Jan 25, 2022 by Dan Carpenter Committed by Mark Brown Feb 08, 2022

spi: spidev: prevent spidev->speed_hz from being zero

A zero value for spi->max_speed_hz or spidev->speed_hz does not make
sense and trying to set that can lead to divide by zero crashes in
a some of the drivers.

drivers/spi/spi-s3c64xx.c:874 s3c64xx_spi_setup() error: potential divide by zero bug '/ spi->max_speed_hz'.
drivers/spi/spi-fsl-dspi.c:613 hz_to_spi_baud() error: potential divide by zero bug '/ speed_hz'.
drivers/spi/spi-xlp.c:146 xlp_spi_setup() error: potential divide by zero bug '/ (spi->max_speed_hz)'.
drivers/spi/spi-orion.c:162 orion_spi_baudrate_set() error: potential divide by zero bug '/ speed'.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20220125065202.GA8807@kili

Signed-off-by: Mark Brown <broonie@kernel.org>

parent 4e28b222

drivers/spi/spidev.c

+19 −12

Original line number	Diff line number	Diff line
		@@ -453,22 +453,29 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
		dev_dbg(&spi->dev, "%d bits per word\n", tmp);
		}
		break;
		case SPI_IOC_WR_MAX_SPEED_HZ:
		case SPI_IOC_WR_MAX_SPEED_HZ: {
		u32 save;

		retval = get_user(tmp, (__u32 __user *)arg);
		if (retval == 0) {
		u32 save = spi->max_speed_hz;
		if (retval)
		break;
		if (tmp == 0) {
		retval = -EINVAL;
		break;
		}

		save = spi->max_speed_hz;

		spi->max_speed_hz = tmp;
		retval = spi_setup(spi);
		if (retval == 0) {
		spidev->speed_hz = tmp;
		dev_dbg(&spi->dev, "%d Hz (max)\n",
		spidev->speed_hz);
		dev_dbg(&spi->dev, "%d Hz (max)\n", spidev->speed_hz);
		}

		spi->max_speed_hz = save;
		}
		break;

		}
		default:
		/* segmented and/or full-duplex I/O request */
		/* Check message and copy into scratch area */