5 files changed, 36 insertions, 27 deletions

diff --git a/drivers/char/selection.c b/drivers/char/selection.c
index 71093a9fc462..74cff839c857 100644
--- a/drivers/char/selection.c
+++ b/drivers/char/selection.c
@@ -33,7 +33,7 @@ extern void poke_blanked_console(void);
 
 /* Variables for selection control. */
 /* Use a dynamic buffer, instead of static (Dec 1994) */
-struct vc_data *sel_cons;               /* must not be disallocated */
+struct vc_data *sel_cons;               /* must not be deallocated */
 static volatile int sel_start = -1;     /* cleared by clear_selection */
 static int sel_end;
 static int sel_buffer_lth;
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index eb881cfa53e0..2a1e95b0f282 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2770,12 +2770,11 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
  *      actually has driver level meaning and triggers a VC resize.
  *
  *      Locking:
- *              The console_sem is used to ensure we do not try and resize
- *      the console twice at once.
- *      FIXME: Two racing size sets may leave the console and kernel
- *              parameters disagreeing. Is this exploitable ?
- *      FIXME: Random values racing a window size get is wrong
- *      should lock here against that
+ *              Called function use the console_sem is used to ensure we do
+ *      not try and resize the console twice at once.
+ *              The tty->termios_sem is used to ensure we don't double
+ *      resize and get confused. Lock order - tty->termios.sem before
+ *      console sem
  */
 
 static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
@@ -2785,17 +2784,17 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
 
         if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
                 return -EFAULT;
+
+        down(&tty->termios_sem);
         if (!memcmp(&tmp_ws, &tty->winsize, sizeof(*arg)))
-                return 0;
+                goto done;
+
 #ifdef CONFIG_VT
         if (tty->driver->type == TTY_DRIVER_TYPE_CONSOLE) {
-                int rc;
-
-                acquire_console_sem();
-                rc = vc_resize(tty->driver_data, tmp_ws.ws_col, tmp_ws.ws_row);
-                release_console_sem();
-                if (rc)
-                        return -ENXIO;
+                if (vc_lock_resize(tty->driver_data, tmp_ws.ws_col, tmp_ws.ws_row)) {
+                        up(&tty->termios_sem);
+                        return -ENXIO;
+                }
         }
 #endif
         if (tty->pgrp > 0)
@@ -2804,6 +2803,8 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
                 kill_pg(real_tty->pgrp, SIGWINCH, 1);
         tty->winsize = tmp_ws;
         real_tty->winsize = tmp_ws;
+done:
+        up(&tty->termios_sem);
         return 0;
 }
 
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 0fca83ededff..b49f03375439 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -885,8 +885,17 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
         return err;
 }
 
+int vc_lock_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)
+{
+        int rc;
+
+        acquire_console_sem();
+        rc = vc_resize(vc, cols, lines);
+        release_console_sem();
+        return rc;
+}
 
-void vc_disallocate(unsigned int currcons)
+void vc_deallocate(unsigned int currcons)
 {
         WARN_CONSOLE_UNLOCKED();
 
@@ -3790,6 +3799,7 @@ EXPORT_SYMBOL(default_blu);
 EXPORT_SYMBOL(update_region);
 EXPORT_SYMBOL(redraw_screen);
 EXPORT_SYMBOL(vc_resize);
+EXPORT_SYMBOL(vc_lock_resize);
 EXPORT_SYMBOL(fg_console);
 EXPORT_SYMBOL(console_blank_hook);
 EXPORT_SYMBOL(console_blanked);
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index a5628a8b6620..a53e382cc107 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -96,7 +96,7 @@ do_kdsk_ioctl(int cmd, struct kbentry __user *user_kbe, int perm, struct kbd_str
                 if (!perm)
                         return -EPERM;
                 if (!i && v == K_NOSUCHMAP) {
-                        /* disallocate map */
+                        /* deallocate map */
                         key_map = key_maps[s];
                         if (s && key_map) {
                             key_maps[s] = NULL;
@@ -819,20 +819,20 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
                 if (arg > MAX_NR_CONSOLES)
                         return -ENXIO;
                 if (arg == 0) {
-                    /* disallocate all unused consoles, but leave 0 */
+                    /* deallocate all unused consoles, but leave 0 */
                         acquire_console_sem();
                         for (i=1; i<MAX_NR_CONSOLES; i++)
                                 if (! VT_BUSY(i))
-                                        vc_disallocate(i);
+                                        vc_deallocate(i);
                         release_console_sem();
                 } else {
-                        /* disallocate a single console, if possible */
+                        /* deallocate a single console, if possible */
                         arg--;
                         if (VT_BUSY(arg))
                                 return -EBUSY;
                         if (arg) {                            /* leave 0 */
                                 acquire_console_sem();
-                                vc_disallocate(arg);
+                                vc_deallocate(arg);
                                 release_console_sem();
                         }
                 }
@@ -847,11 +847,8 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
                 if (get_user(ll, &vtsizes->v_rows) ||
                     get_user(cc, &vtsizes->v_cols))
                         return -EFAULT;
-                for (i = 0; i < MAX_NR_CONSOLES; i++) {
-                        acquire_console_sem();
-                        vc_resize(vc_cons[i].d, cc, ll);
-                        release_console_sem();
-                }
+                for (i = 0; i < MAX_NR_CONSOLES; i++)
+                        vc_lock_resize(vc_cons[i].d, cc, ll);
                 return 0;
         }
 
diff --git a/include/linux/vt_kern.h b/include/linux/vt_kern.h
index 918a29763aea..1009d3fe1fc2 100644
--- a/include/linux/vt_kern.h
+++ b/include/linux/vt_kern.h
@@ -33,7 +33,8 @@ extern int fg_console, last_console, want_console;
 int vc_allocate(unsigned int console);
 int vc_cons_allocated(unsigned int console);
 int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines);
-void vc_disallocate(unsigned int console);
+int vc_lock_resize(struct vc_data *vc, unsigned int cols, unsigned int lines);
+void vc_deallocate(unsigned int console);
 void reset_palette(struct vc_data *vc);
 void do_blank_screen(int entering_gfx);
 void do_unblank_screen(int leaving_gfx);