misc: xilinx_sdfec: Prevent a divide by zero in xsdfec_reg0_write()

The "psize" value comes from the user so we need to verify that it's
non-zero before we check if "n % psize" or it will crash.

Fixes: 20ec628e8007 ("misc: xilinx_sdfec: Add ability to configure LDPC")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/20190821070953.GC26957@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
index 813b82c5936035c1060472a8876cdae743d29120..3fc53d20abf374f53fd0c85ed71775f14ae2e097 100644 (file)
--- a/drivers/misc/xilinx_sdfec.c
+++ b/drivers/misc/xilinx_sdfec.c
@@ -460,7 +460,7 @@ static int xsdfec_reg0_write(struct xsdfec_dev *xsdfec, u32 n, u32 k, u32 psize,
 {
        u32 wdata;
 
-       if (n < XSDFEC_REG0_N_MIN || n > XSDFEC_REG0_N_MAX ||
+       if (n < XSDFEC_REG0_N_MIN || n > XSDFEC_REG0_N_MAX || psize == 0 ||
            (n > XSDFEC_REG0_N_MUL_P * psize) || n <= k || ((n % psize) != 0)) {
                dev_dbg(xsdfec->dev, "N value is not in range");
                return -EINVAL;