V4L/DVB (5935): dvb_frontend: Range check of frequency and symbol rate

Add range check of frequency and symbol rate to the FE_SET_FRONTEND ioctl.

This will also avoid a divide-by zero exception in the stv0297 driver,
if symbol rate is set to 0.

Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/media/dvb/dvb-core/dvb_frontend.c b/drivers/media/dvb/dvb-core/dvb_frontend.c
index b6c7f6610ec5..384b5b8959c1 100644
--- a/drivers/media/dvb/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb/dvb-core/dvb_frontend.c
@@ -697,6 +697,47 @@ static int dvb_frontend_start(struct dvb_frontend *fe)
         return 0;
 }
 
+static int dvb_frontend_check_parameters(struct dvb_frontend *fe,
+                                struct dvb_frontend_parameters *parms)
+{
+        /* range check: frequency */
+        if ((fe->ops.info.frequency_min &&
+             parms->frequency < fe->ops.info.frequency_min) ||
+            (fe->ops.info.frequency_max &&
+             parms->frequency > fe->ops.info.frequency_max)) {
+                printk(KERN_WARNING "DVB: frontend %u frequency %u out of range (%u..%u)\n",
+                       fe->dvb->num, parms->frequency,
+                       fe->ops.info.frequency_min, fe->ops.info.frequency_max);
+                return -EINVAL;
+        }
+
+        /* range check: symbol rate */
+        if (fe->ops.info.type == FE_QPSK) {
+                if ((fe->ops.info.symbol_rate_min &&
+                     parms->u.qpsk.symbol_rate < fe->ops.info.symbol_rate_min) ||
+                    (fe->ops.info.symbol_rate_max &&
+                     parms->u.qpsk.symbol_rate > fe->ops.info.symbol_rate_max)) {
+                        printk(KERN_WARNING "DVB: frontend %u symbol rate %u out of range (%u..%u)\n",
+                               fe->dvb->num, parms->u.qpsk.symbol_rate,
+                               fe->ops.info.symbol_rate_min, fe->ops.info.symbol_rate_max);
+                        return -EINVAL;
+                }
+
+        } else if (fe->ops.info.type == FE_QAM) {
+                if ((fe->ops.info.symbol_rate_min &&
+                     parms->u.qam.symbol_rate < fe->ops.info.symbol_rate_min) ||
+                    (fe->ops.info.symbol_rate_max &&
+                     parms->u.qam.symbol_rate > fe->ops.info.symbol_rate_max)) {
+                        printk(KERN_WARNING "DVB: frontend %u symbol rate %u out of range (%u..%u)\n",
+                               fe->dvb->num, parms->u.qam.symbol_rate,
+                               fe->ops.info.symbol_rate_min, fe->ops.info.symbol_rate_max);
+                        return -EINVAL;
+                }
+        }
+
+        return 0;
+}
+
 static int dvb_frontend_ioctl(struct inode *inode, struct file *file,
                         unsigned int cmd, void *parg)
 {
@@ -883,6 +924,11 @@ static int dvb_frontend_ioctl(struct inode *inode, struct file *file,
         case FE_SET_FRONTEND: {
                 struct dvb_frontend_tune_settings fetunesettings;
 
+                if (dvb_frontend_check_parameters(fe, parg) < 0) {
+                        err = -EINVAL;
+                        break;
+                }
+
                 memcpy (&fepriv->parameters, parg,
                         sizeof (struct dvb_frontend_parameters));