1 files changed, 17 insertions, 2 deletions

diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c
index b26e509ec759..9f6c6375ff75 100644
--- a/drivers/isdn/i4l/isdn_common.c
+++ b/drivers/isdn/i4l/isdn_common.c
@@ -11,7 +11,6 @@
  *
  */
 
-#include <linux/config.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/poll.h>
@@ -340,6 +339,16 @@ isdn_command(isdn_ctrl *cmd)
                 printk(KERN_WARNING "isdn_command command(%x) driver -1\n", cmd->command);
                 return(1);
         }
+        if (!dev->drv[cmd->driver]) {
+                printk(KERN_WARNING "isdn_command command(%x) dev->drv[%d] NULL\n",
+                        cmd->command, cmd->driver);
+                return(1);
+        }
+        if (!dev->drv[cmd->driver]->interface) {
+                printk(KERN_WARNING "isdn_command command(%x) dev->drv[%d]->interface NULL\n",
+                        cmd->command, cmd->driver);
+                return(1);
+        }
         if (cmd->command == ISDN_CMD_SETL2) {
                 int idx = isdn_dc2minor(cmd->driver, cmd->arg & 255);
                 unsigned long l2prot = (cmd->arg >> 8) & 255;
@@ -1903,6 +1912,11 @@ isdn_free_channel(int di, int ch, int usage)
 {
         int i;
 
+        if ((di < 0) || (ch < 0)) {
+                printk(KERN_WARNING "%s: called with invalid drv(%d) or channel(%d)\n",
+                        __FUNCTION__, di, ch);
+                return;
+        }
         for (i = 0; i < ISDN_MAX_CHANNELS; i++)
                 if (((!usage) || ((dev->usage[i] & ISDN_USAGE_MASK) == usage)) &&
                     (dev->drvmap[i] == di) &&
@@ -1918,7 +1932,8 @@ isdn_free_channel(int di, int ch, int usage)
                         dev->v110[i] = NULL;
 // 20.10.99 JIM, try to reinitialize v110 !
                         isdn_info_update();
-                        skb_queue_purge(&dev->drv[di]->rpqueue[ch]);
+                        if (dev->drv[di])
+                                skb_queue_purge(&dev->drv[di]->rpqueue[ch]);
                 }
 }