summaryrefslogtreecommitdiffstats
path: root/drivers/char/tty_io.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/char/tty_io.c')
-rw-r--r--drivers/char/tty_io.c104
1 files changed, 53 insertions, 51 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index bb0d9199e99..333741770f1 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -129,6 +129,7 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */
/* Semaphore to protect creating and releasing a tty. This is shared with
vt.c for deeply disgusting hack reasons */
DEFINE_MUTEX(tty_mutex);
+EXPORT_SYMBOL(tty_mutex);
#ifdef CONFIG_UNIX98_PTYS
extern struct tty_driver *ptm_driver; /* Unix98 pty masters; for /dev/ptmx */
@@ -160,17 +161,11 @@ static void release_mem(struct tty_struct *tty, int idx);
* been initialized in any way but has been zeroed
*
* Locking: none
- * FIXME: use kzalloc
*/
static struct tty_struct *alloc_tty_struct(void)
{
- struct tty_struct *tty;
-
- tty = kmalloc(sizeof(struct tty_struct), GFP_KERNEL);
- if (tty)
- memset(tty, 0, sizeof(struct tty_struct));
- return tty;
+ return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
}
static void tty_buffer_free_all(struct tty_struct *);
@@ -483,10 +478,9 @@ int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars,
tb->used += space;
copied += space;
chars += space;
- }
- /* There is a small chance that we need to split the data over
- several buffers. If this is the case we must loop */
- while (unlikely(size > copied));
+ /* There is a small chance that we need to split the data over
+ several buffers. If this is the case we must loop */
+ } while (unlikely(size > copied));
return copied;
}
EXPORT_SYMBOL(tty_insert_flip_string);
@@ -521,10 +515,9 @@ int tty_insert_flip_string_flags(struct tty_struct *tty,
copied += space;
chars += space;
flags += space;
- }
- /* There is a small chance that we need to split the data over
- several buffers. If this is the case we must loop */
- while (unlikely(size > copied));
+ /* There is a small chance that we need to split the data over
+ several buffers. If this is the case we must loop */
+ } while (unlikely(size > copied));
return copied;
}
EXPORT_SYMBOL(tty_insert_flip_string_flags);
@@ -626,9 +619,9 @@ EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags);
static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
{
- down(&tty->termios_sem);
+ mutex_lock(&tty->termios_mutex);
tty->termios->c_line = num;
- up(&tty->termios_sem);
+ mutex_unlock(&tty->termios_mutex);
}
/*
@@ -1346,9 +1339,9 @@ static void do_tty_hangup(void *data)
*/
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
{
- down(&tty->termios_sem);
+ mutex_lock(&tty->termios_mutex);
*tty->termios = tty->driver->init_termios;
- up(&tty->termios_sem);
+ mutex_unlock(&tty->termios_mutex);
}
/* Defer ldisc switch */
@@ -2072,8 +2065,9 @@ fail_no_mem:
/* call the tty release_mem routine to clean out this slot */
release_mem_out:
- printk(KERN_INFO "init_dev: ldisc open failed, "
- "clearing slot %d\n", idx);
+ if (printk_ratelimit())
+ printk(KERN_INFO "init_dev: ldisc open failed, "
+ "clearing slot %d\n", idx);
release_mem(tty, idx);
goto end_init;
}
@@ -2726,6 +2720,8 @@ static int tty_fasync(int fd, struct file * filp, int on)
* Locking:
* Called functions take tty_ldisc_lock
* current->signal->tty check is safe without locks
+ *
+ * FIXME: may race normal receive processing
*/
static int tiocsti(struct tty_struct *tty, char __user *p)
@@ -2748,18 +2744,21 @@ static int tiocsti(struct tty_struct *tty, char __user *p)
* @tty; tty
* @arg: user buffer for result
*
- * Copies the kernel idea of the window size into the user buffer. No
- * locking is done.
+ * Copies the kernel idea of the window size into the user buffer.
*
- * FIXME: Returning random values racing a window size set is wrong
- * should lock here against that
+ * Locking: tty->termios_sem is taken to ensure the winsize data
+ * is consistent.
*/
static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg)
{
- if (copy_to_user(arg, &tty->winsize, sizeof(*arg)))
- return -EFAULT;
- return 0;
+ int err;
+
+ mutex_lock(&tty->termios_mutex);
+ err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
+ mutex_unlock(&tty->termios_mutex);
+
+ return err ? -EFAULT: 0;
}
/**
@@ -2772,12 +2771,11 @@ 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,
@@ -2787,17 +2785,18 @@ static int tiocswinsz(struct tty_struct *tty, struct tty_struct *real_tty,
if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
return -EFAULT;
+
+ mutex_lock(&tty->termios_mutex);
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)) {
+ mutex_unlock(&tty->termios_mutex);
+ return -ENXIO;
+ }
}
#endif
if (tty->pgrp > 0)
@@ -2806,6 +2805,8 @@ 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:
+ mutex_unlock(&tty->termios_mutex);
return 0;
}
@@ -2880,9 +2881,7 @@ static int fionbio(struct file *file, int __user *p)
* Locking:
* Takes tasklist lock internally to walk sessions
* Takes task_lock() when updating signal->tty
- *
- * FIXME: tty_mutex is needed to protect signal->tty references.
- * FIXME: why task_lock on the signal->tty reference ??
+ * Takes tty_mutex() to protect tty instance
*
*/
@@ -2917,9 +2916,11 @@ static int tiocsctty(struct tty_struct *tty, int arg)
} else
return -EPERM;
}
+ mutex_lock(&tty_mutex);
task_lock(current);
current->signal->tty = tty;
task_unlock(current);
+ mutex_unlock(&tty_mutex);
current->signal->tty_old_pgrp = 0;
tty->session = current->signal->session;
tty->pgrp = process_group(current);
@@ -2959,8 +2960,6 @@ static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t
* permitted where the tty session is our session.
*
* Locking: None
- *
- * FIXME: current->signal->tty referencing is unsafe.
*/
static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
@@ -3039,19 +3038,20 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
* timed break functionality.
*
* Locking:
- * None
+ * atomic_write_lock serializes
*
- * FIXME:
- * What if two overlap
*/
static int send_break(struct tty_struct *tty, unsigned int duration)
{
+ if (mutex_lock_interruptible(&tty->atomic_write_lock))
+ return -EINTR;
tty->driver->break_ctl(tty, -1);
if (!signal_pending(current)) {
msleep_interruptible(duration);
}
tty->driver->break_ctl(tty, 0);
+ mutex_unlock(&tty->atomic_write_lock);
if (signal_pending(current))
return -EINTR;
return 0;
@@ -3144,6 +3144,8 @@ int tty_ioctl(struct inode * inode, struct file * file,
if (tty_paranoia_check(tty, inode, "tty_ioctl"))
return -EINVAL;
+ /* CHECKME: is this safe as one end closes ? */
+
real_tty = tty;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
@@ -3580,7 +3582,7 @@ static void initialize_tty_struct(struct tty_struct *tty)
tty_buffer_init(tty);
INIT_WORK(&tty->buf.work, flush_to_ldisc, tty);
init_MUTEX(&tty->buf.pty_sem);
- init_MUTEX(&tty->termios_sem);
+ mutex_init(&tty->termios_mutex);
init_waitqueue_head(&tty->write_wait);
init_waitqueue_head(&tty->read_wait);
INIT_WORK(&tty->hangup_work, do_tty_hangup, tty);
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-25 20:38:27 +0000