diff options
author | Jiri Slaby <jslaby@suse.cz> | 2011-11-11 10:47:23 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-15 15:52:47 -0800 |
commit | 955787ca94a17bdfd00e369a21ceb97aa21792fc (patch) | |
tree | 16bd8e8a7c154be15dcb0c7375c4c8c2c7c019c9 /drivers/tty/tty_io.c | |
parent | 2cd0050cf3ec4da847c3a2f7d95cffd548aef39d (diff) | |
download | op-kernel-dev-955787ca94a17bdfd00e369a21ceb97aa21792fc.zip op-kernel-dev-955787ca94a17bdfd00e369a21ceb97aa21792fc.tar.gz |
TTY: move debug checking out of tty_release
There is no need to taint the tty_release code with paranoia
checking. So move it out of line to a separate function. Making thus
tty_release more readable.
[v2] don't introduce a hard to reproduce use after free (scheduled work would
need to preempt the current thread)
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty/tty_io.c')
-rw-r--r-- | drivers/tty/tty_io.c | 101 |
1 files changed, 57 insertions, 44 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 76e66ff..b874b6d 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1557,6 +1557,62 @@ static void release_tty(struct tty_struct *tty, int idx) } /** + * tty_release_checks - check a tty before real release + * @tty: tty to check + * @o_tty: link of @tty (if any) + * @idx: index of the tty + * + * Performs some paranoid checking before true release of the @tty. + * This is a no-op unless TTY_PARANOIA_CHECK is defined. + */ +static int tty_release_checks(struct tty_struct *tty, struct tty_struct *o_tty, + int idx) +{ +#ifdef TTY_PARANOIA_CHECK + if (idx < 0 || idx >= tty->driver->num) { + printk(KERN_DEBUG "tty_release_dev: bad idx when trying to " + "free (%s)\n", tty->name); + return -1; + } + + /* not much to check for devpts */ + if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) + return 0; + + if (tty != tty->driver->ttys[idx]) { + printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty " + "for (%s)\n", idx, tty->name); + return -1; + } + if (tty->termios != tty->driver->termios[idx]) { + printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios " + "for (%s)\n", + idx, tty->name); + return -1; + } + if (tty->driver->other) { + if (o_tty != tty->driver->other->ttys[idx]) { + printk(KERN_DEBUG "tty_release_dev: other->table[%d] " + "not o_tty for (%s)\n", + idx, tty->name); + return -1; + } + if (o_tty->termios != tty->driver->other->termios[idx]) { + printk(KERN_DEBUG "tty_release_dev: other->termios[%d] " + "not o_termios for (%s)\n", + idx, tty->name); + return -1; + } + if (o_tty->link != tty) { + printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n"); + return -1; + } + } +#endif + return 0; +} + +/** * tty_release - vfs callback for close * @inode: inode of tty * @filp: file pointer for handle to tty @@ -1598,59 +1654,16 @@ int tty_release(struct inode *inode, struct file *filp) devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0; o_tty = tty->link; -#ifdef TTY_PARANOIA_CHECK - if (idx < 0 || idx >= tty->driver->num) { - printk(KERN_DEBUG "tty_release_dev: bad idx when trying to " - "free (%s)\n", tty->name); + if (tty_release_checks(tty, o_tty, idx)) { tty_unlock(); return 0; } - if (!devpts) { - if (tty != tty->driver->ttys[idx]) { - tty_unlock(); - printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty " - "for (%s)\n", idx, tty->name); - return 0; - } - if (tty->termios != tty->driver->termios[idx]) { - tty_unlock(); - printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios " - "for (%s)\n", - idx, tty->name); - return 0; - } - } -#endif #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...", tty_name(tty, buf), tty->count); #endif -#ifdef TTY_PARANOIA_CHECK - if (tty->driver->other && - !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) { - if (o_tty != tty->driver->other->ttys[idx]) { - tty_unlock(); - printk(KERN_DEBUG "tty_release_dev: other->table[%d] " - "not o_tty for (%s)\n", - idx, tty->name); - return 0 ; - } - if (o_tty->termios != tty->driver->other->termios[idx]) { - tty_unlock(); - printk(KERN_DEBUG "tty_release_dev: other->termios[%d] " - "not o_termios for (%s)\n", - idx, tty->name); - return 0; - } - if (o_tty->link != tty) { - tty_unlock(); - printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n"); - return 0; - } - } -#endif if (tty->ops->close) tty->ops->close(tty, filp); |