[PATCH] hvc_console: Add some sanity checks

Check if a vterm was registered before accepting it as a console.
Check that a slot hasn't been probed with a tty in hvc_instantiate().
Check that a slot hasn't been free'ed when handing out console device.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index de849f571ea2..7bc65a76dfc4 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -192,12 +192,21 @@ void hvc_console_print(struct console *co, const char *b, unsigned count)
 
 static struct tty_driver *hvc_console_device(struct console *c, int *index)
 {
+        if (vtermnos[c->index] == -1)
+                return NULL;
+
         *index = c->index;
         return hvc_driver;
 }
 
 static int __init hvc_console_setup(struct console *co, char *options)
 {
+        if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
+                return -ENODEV;
+
+        if (vtermnos[co->index] == -1)
+                return -ENODEV;
+
         return 0;
 }
 
@@ -227,12 +236,21 @@ console_initcall(hvc_console_init);
  */
 int hvc_instantiate(uint32_t vtermno, int index)
 {
+        struct hvc_struct *hp;
+
         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
                 return -1;
 
         if (vtermnos[index] != -1)
                 return -1;
 
+        /* make sure no no tty has been registerd in this index */
+        hp = hvc_get_by_index(index);
+        if (hp) {
+                kobject_put(&hp->kobj);
+                return -1;
+        }
+
         vtermnos[index] = vtermno;
 
         /* reserve all indices upto and including this index */