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Subject[PATCH 34/76] tty: Termios locking - sort out real_tty confusions and lock reads
Date
This moves us towards sanity and should mean our termios locking is now
complete and comprehensive.
---

drivers/char/tty_io.c | 2 +-
drivers/char/tty_ioctl.c | 58 ++++++++++++++++++++++++++++++----------------
2 files changed, 39 insertions(+), 21 deletions(-)

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index fa162c9..ac53d7f 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2605,7 +2605,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
case TIOCSTI:
return tiocsti(tty, p);
case TIOCGWINSZ:
- return tiocgwinsz(tty, p);
+ return tiocgwinsz(real_tty, p);
case TIOCSWINSZ:
return tiocswinsz(tty, real_tty, p);
case TIOCCONS:
diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index 93bfa1d..3067085 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -893,6 +893,7 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
{
struct tty_struct *real_tty;
void __user *p = (void __user *)arg;
+ int ret = 0;

if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
@@ -928,18 +929,24 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
return set_termios(real_tty, p, TERMIOS_OLD);
#ifndef TCGETS2
case TCGETS:
+ mutex_lock(&real_tty->termios_mutex);
if (kernel_termios_to_user_termios((struct termios __user *)arg, real_tty->termios))
- return -EFAULT;
- return 0;
+ ret = -EFAULT;
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
#else
case TCGETS:
+ mutex_lock(&real_tty->termios_mutex);
if (kernel_termios_to_user_termios_1((struct termios __user *)arg, real_tty->termios))
- return -EFAULT;
- return 0;
+ ret = -EFAULT;
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
case TCGETS2:
+ mutex_lock(&real_tty->termios_mutex);
if (kernel_termios_to_user_termios((struct termios2 __user *)arg, real_tty->termios))
- return -EFAULT;
- return 0;
+ ret = -EFAULT;
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
case TCSETSF2:
return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT);
case TCSETSW2:
@@ -957,36 +964,46 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
return set_termios(real_tty, p, TERMIOS_TERMIO);
#ifndef TCGETS2
case TIOCGLCKTRMIOS:
+ mutex_lock(&real_tty->termios_mutex);
if (kernel_termios_to_user_termios((struct termios __user *)arg, real_tty->termios_locked))
- return -EFAULT;
- return 0;
+ ret = -EFAULT;
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
case TIOCSLCKTRMIOS:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+ mutex_lock(&real_tty->termios_mutex);
if (user_termios_to_kernel_termios(real_tty->termios_locked,
(struct termios __user *) arg))
- return -EFAULT;
- return 0;
+ ret = -EFAULT;
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
#else
case TIOCGLCKTRMIOS:
+ mutex_lock(&real_tty->termios_mutex);
if (kernel_termios_to_user_termios_1((struct termios __user *)arg, real_tty->termios_locked))
- return -EFAULT;
- return 0;
+ ret = -EFAULT;
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
case TIOCSLCKTRMIOS:
if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
+ ret = -EPERM;
+ mutex_lock(&real_tty->termios_mutex);
if (user_termios_to_kernel_termios_1(real_tty->termios_locked,
(struct termios __user *) arg))
- return -EFAULT;
- return 0;
+ ret = -EFAULT;
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
#endif
#ifdef TCGETX
case TCGETX:
if (real_tty->termiox == NULL)
return -EINVAL;
+ mutex_lock(&real_tty->termios_mutex);
if (copy_to_user(p, real_tty->termiox, sizeof(struct termiox)))
- return -EFAULT;
- return 0;
+ ret = -EFAULT;
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
case TCSETX:
return set_termiox(real_tty, p, 0);
case TCSETXW:
@@ -995,10 +1012,11 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
return set_termiox(real_tty, p, TERMIOS_FLUSH);
#endif
case TIOCGSOFTCAR:
- /* FIXME: for correctness we may need to take the termios
- lock here - review */
- return put_user(C_CLOCAL(real_tty) ? 1 : 0,
+ mutex_lock(&real_tty->termios_mutex);
+ ret = put_user(C_CLOCAL(real_tty) ? 1 : 0,
(int __user *)arg);
+ mutex_unlock(&real_tty->termios_mutex);
+ return ret;
case TIOCSSOFTCAR:
if (get_user(arg, (unsigned int __user *) arg))
return -EFAULT;


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