Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d5698c28b6e4711e4747bf155f69936208d60e28
Commit: d5698c28b6e4711e4747bf155f69936208d60e28
Parent: 4b98d11b40f03382918796f3c5c936d5495d20a4
Author: Christoph Hellwig <[EMAIL PROTECTED]>
AuthorDate: Sat Feb 10 01:46:46 2007 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Sun Feb 11 11:18:07 2007 -0800
[PATCH] tty: cleanup release_mem
release_mem contains two copies of exactly the same code. Refactor these
into a new helper, release_tty. The only change in behaviour is that the
driver reference count is now decremented after the master tty has been
freed instead of before.
[EMAIL PROTECTED]: fix use-after-free in release_tty.]
Cc: Alan Cox <[EMAIL PROTECTED]>
Signed-off-by: Christoph Hellwig <[EMAIL PROTECTED]>
Signed-off-by: Pekka Enberg <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
drivers/char/tty_io.c | 73 +++++++++++++++++++++++++------------------------
1 files changed, 37 insertions(+), 36 deletions(-)
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 305e46d..558ca92 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -154,7 +154,7 @@ static int tty_release(struct inode *, struct file *);
int tty_ioctl(struct inode * inode, struct file * file,
unsigned int cmd, unsigned long arg);
static int tty_fasync(int fd, struct file * filp, int on);
-static void release_mem(struct tty_struct *tty, int idx);
+static void release_tty(struct tty_struct *tty, int idx);
/**
* alloc_tty_struct - allocate a tty object
@@ -2002,7 +2002,7 @@ static int init_dev(struct tty_driver *driver, int idx,
/*
* All structures have been allocated, so now we install them.
- * Failures after this point use release_mem to clean up, so
+ * Failures after this point use release_tty to clean up, so
* there's no need to null out the local pointers.
*/
if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
@@ -2023,8 +2023,8 @@ static int init_dev(struct tty_driver *driver, int idx,
/*
* Structures all installed ... call the ldisc open routines.
- * If we fail here just call release_mem to clean up. No need
- * to decrement the use counts, as release_mem doesn't care.
+ * If we fail here just call release_tty to clean up. No need
+ * to decrement the use counts, as release_tty doesn't care.
*/
if (tty->ldisc.open) {
@@ -2094,17 +2094,17 @@ fail_no_mem:
retval = -ENOMEM;
goto end_init;
- /* call the tty release_mem routine to clean out this slot */
+ /* call the tty release_tty routine to clean out this slot */
release_mem_out:
if (printk_ratelimit())
printk(KERN_INFO "init_dev: ldisc open failed, "
"clearing slot %d\n", idx);
- release_mem(tty, idx);
+ release_tty(tty, idx);
goto end_init;
}
/**
- * release_mem - release tty structure memory
+ * release_one_tty - release tty structure memory
*
* Releases memory associated with a tty structure, and clears out the
* driver table slots. This function is called when a device is no longer
@@ -2116,37 +2116,14 @@ release_mem_out:
* of ttys that the driver keeps.
* FIXME: should we require tty_mutex is held here ??
*/
-
-static void release_mem(struct tty_struct *tty, int idx)
+static void release_one_tty(struct tty_struct *tty, int idx)
{
- struct tty_struct *o_tty;
- struct ktermios *tp;
int devpts = tty->driver->flags & TTY_DRIVER_DEVPTS_MEM;
-
- if ((o_tty = tty->link) != NULL) {
- if (!devpts)
- o_tty->driver->ttys[idx] = NULL;
- if (o_tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
- tp = o_tty->termios;
- if (!devpts)
- o_tty->driver->termios[idx] = NULL;
- kfree(tp);
-
- tp = o_tty->termios_locked;
- if (!devpts)
- o_tty->driver->termios_locked[idx] = NULL;
- kfree(tp);
- }
- o_tty->magic = 0;
- o_tty->driver->refcount--;
- file_list_lock();
- list_del_init(&o_tty->tty_files);
- file_list_unlock();
- free_tty_struct(o_tty);
- }
+ struct ktermios *tp;
if (!devpts)
tty->driver->ttys[idx] = NULL;
+
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
tp = tty->termios;
if (!devpts)
@@ -2159,15 +2136,39 @@ static void release_mem(struct tty_struct *tty, int idx)
kfree(tp);
}
+
tty->magic = 0;
tty->driver->refcount--;
+
file_list_lock();
list_del_init(&tty->tty_files);
file_list_unlock();
- module_put(tty->driver->owner);
+
free_tty_struct(tty);
}
+/**
+ * release_tty - release tty structure memory
+ *
+ * Release both @tty and a possible linked partner (think pty pair),
+ * and decrement the refcount of the backing module.
+ *
+ * Locking:
+ * tty_mutex - sometimes only
+ * takes the file list lock internally when working on the list
+ * of ttys that the driver keeps.
+ * FIXME: should we require tty_mutex is held here ??
+ */
+static void release_tty(struct tty_struct *tty, int idx)
+{
+ struct tty_driver *driver = tty->driver;
+
+ if (tty->link)
+ release_one_tty(tty->link, idx);
+ release_one_tty(tty, idx);
+ module_put(driver->owner);
+}
+
/*
* Even releasing the tty structures is a tricky business.. We have
* to be very careful that the structures are all released at the
@@ -2435,10 +2436,10 @@ static void release_dev(struct file * filp)
tty_set_termios_ldisc(o_tty,N_TTY);
}
/*
- * The release_mem function takes care of the details of clearing
+ * The release_tty function takes care of the details of clearing
* the slots and preserving the termios structure.
*/
- release_mem(tty, idx);
+ release_tty(tty, idx);
#ifdef CONFIG_UNIX98_PTYS
/* Make this pty number available for reallocation */
-
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