The patch titled
tty: ->signal->tty locking
has been removed from the -mm tree. Its filename was
tty-signal-tty-locking.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: tty: ->signal->tty locking
From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Fix the locking of signal->tty.
Use ->sighand->siglock to protect ->signal->tty; this lock is already used
by most other members of ->signal/->sighand. And unless we are 'current'
or the tasklist_lock is held we need ->siglock to access ->signal anyway.
(NOTE: sys_unshare() is broken wrt ->sighand locking rules)
Note that tty_mutex is held over tty destruction, so while holding
tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys
are governed by their open file handles. This leaves some holes for tty
access from signal->tty (or any other non file related tty access).
It solves the tty SLAB scribbles we were seeing.
(NOTE: the change from group_send_sig_info to __group_send_sig_info needs to
be examined by someone familiar with the security framework, I think
it is safe given the SEND_SIG_PRIV from other __group_send_sig_info
invocations)
[schwidefsky@xxxxxxxxxx: 3270 fix]
[akpm@xxxxxxxx: various post-viro fixes]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Acked-by: Alan Cox <alan@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Chris Wright <chrisw@xxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Stephen Smalley <sds@xxxxxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/sparc64/solaris/misc.c | 4
arch/um/kernel/exec.c | 7 -
drivers/char/tty_io.c | 237 ++++++++++++++++++++--------------
drivers/s390/char/fs3270.c | 12 +
fs/dquot.c | 14 +-
fs/open.c | 1
include/linux/tty.h | 11 -
kernel/acct.c | 9 -
kernel/auditsc.c | 2
kernel/exit.c | 4
kernel/sys.c | 6
security/selinux/hooks.c | 11 +
12 files changed, 186 insertions(+), 132 deletions(-)
diff -puN arch/sparc64/solaris/misc.c~tty-signal-tty-locking arch/sparc64/solaris/misc.c
--- a/arch/sparc64/solaris/misc.c~tty-signal-tty-locking
+++ a/arch/sparc64/solaris/misc.c
@@ -423,9 +423,7 @@ asmlinkage int solaris_procids(int cmd,
Solaris setpgrp and setsid? */
ret = sys_setpgid(0, 0);
if (ret) return ret;
- mutex_lock(&tty_mutex);
- current->signal->tty = NULL;
- mutex_unlock(&tty_mutex);
+ proc_clear_tty(current);
return process_group(current);
}
case 2: /* getsid */
diff -puN arch/um/kernel/exec.c~tty-signal-tty-locking arch/um/kernel/exec.c
--- a/arch/um/kernel/exec.c~tty-signal-tty-locking
+++ a/arch/um/kernel/exec.c
@@ -39,12 +39,13 @@ static long execve1(char *file, char __u
char __user *__user *env)
{
long error;
+ struct tty_struct *tty;
#ifdef CONFIG_TTY_LOG
mutex_lock(&tty_mutex);
- task_lock(current); /* FIXME: is this needed ? */
- log_exec(argv, current->signal->tty);
- task_unlock(current);
+ tty = get_current_tty();
+ if (tty)
+ log_exec(argv, tty);
mutex_unlock(&tty_mutex);
#endif
error = do_execve(file, argv, env, ¤t->thread.regs);
diff -puN drivers/char/tty_io.c~tty-signal-tty-locking drivers/char/tty_io.c
--- a/drivers/char/tty_io.c~tty-signal-tty-locking
+++ a/drivers/char/tty_io.c
@@ -126,7 +126,7 @@ EXPORT_SYMBOL(tty_std_termios);
LIST_HEAD(tty_drivers); /* linked list of tty drivers */
-/* Semaphore to protect creating and releasing a tty. This is shared with
+/* Mutex 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);
@@ -250,7 +250,7 @@ static int check_tty_count(struct tty_st
"!= #fd's(%d) in %s\n",
tty->name, tty->count, count, routine);
return count;
- }
+ }
#endif
return 0;
}
@@ -259,18 +259,6 @@ static int check_tty_count(struct tty_st
* Tty buffer allocation management
*/
-
-/**
- * tty_buffer_free_all - free buffers used by a tty
- * @tty: tty to free from
- *
- * Remove all the buffers pending on a tty whether queued with data
- * or in the free ring. Must be called when the tty is no longer in use
- *
- * Locking: none
- */
-
-
/**
* tty_buffer_free_all - free buffers used by a tty
* @tty: tty to free from
@@ -614,7 +602,7 @@ EXPORT_SYMBOL_GPL(tty_prepare_flip_strin
* they are not on hot paths so a little discipline won't do
* any harm.
*
- * Locking: takes termios_sem
+ * Locking: takes termios_mutex
*/
static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
@@ -915,7 +903,7 @@ static void tty_ldisc_enable(struct tty_
* context.
*
* Locking: takes tty_ldisc_lock.
- * called functions take termios_sem
+ * called functions take termios_mutex
*/
static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
@@ -1267,12 +1255,12 @@ EXPORT_SYMBOL_GPL(tty_ldisc_flush);
*
* Locking:
* BKL
- * redirect lock for undoing redirection
- * file list lock for manipulating list of ttys
- * tty_ldisc_lock from called functions
- * termios_sem resetting termios data
- * tasklist_lock to walk task list for hangup event
- *
+ * redirect lock for undoing redirection
+ * file list lock for manipulating list of ttys
+ * tty_ldisc_lock from called functions
+ * termios_mutex resetting termios data
+ * tasklist_lock to walk task list for hangup event
+ * ->siglock to protect ->signal/->sighand
*/
static void do_tty_hangup(struct work_struct *work)
{
@@ -1354,14 +1342,18 @@ static void do_tty_hangup(struct work_st
read_lock(&tasklist_lock);
if (tty->session > 0) {
do_each_task_pid(tty->session, PIDTYPE_SID, p) {
+ spin_lock_irq(&p->sighand->siglock);
if (p->signal->tty == tty)
p->signal->tty = NULL;
- if (!p->signal->leader)
+ if (!p->signal->leader) {
+ spin_unlock_irq(&p->sighand->siglock);
continue;
- group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
- group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
+ }
+ __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
+ __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
if (tty->pgrp > 0)
p->signal->tty_old_pgrp = tty->pgrp;
+ spin_unlock_irq(&p->sighand->siglock);
} while_each_task_pid(tty->session, PIDTYPE_SID, p);
}
read_unlock(&tasklist_lock);
@@ -1453,6 +1445,14 @@ int tty_hung_up_p(struct file * filp)
EXPORT_SYMBOL(tty_hung_up_p);
+static void session_clear_tty(pid_t session)
+{
+ struct task_struct *p;
+ do_each_task_pid(session, PIDTYPE_SID, p) {
+ proc_clear_tty(p);
+ } while_each_task_pid(session, PIDTYPE_SID, p);
+}
+
/**
* disassociate_ctty - disconnect controlling tty
* @on_exit: true if exiting so need to "hang up" the session
@@ -1469,31 +1469,35 @@ EXPORT_SYMBOL(tty_hung_up_p);
* The argument on_exit is set to 1 if called when a process is
* exiting; it is 0 if called by the ioctl TIOCNOTTY.
*
- * Locking: tty_mutex is taken to protect current->signal->tty
+ * Locking:
* BKL is taken for hysterical raisins
- * Tasklist lock is taken (under tty_mutex) to walk process
- * lists for the session.
+ * tty_mutex is taken to protect tty
+ * ->siglock is taken to protect ->signal/->sighand
+ * tasklist_lock is taken to walk process list for sessions
+ * ->siglock is taken to protect ->signal/->sighand
*/
void disassociate_ctty(int on_exit)
{
struct tty_struct *tty;
- struct task_struct *p;
int tty_pgrp = -1;
+ int session;
lock_kernel();
mutex_lock(&tty_mutex);
- tty = current->signal->tty;
+ tty = get_current_tty();
if (tty) {
tty_pgrp = tty->pgrp;
mutex_unlock(&tty_mutex);
+ /* XXX: here we race, there is nothing protecting tty */
if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
tty_vhangup(tty);
} else {
- if (current->signal->tty_old_pgrp) {
- kill_pg(current->signal->tty_old_pgrp, SIGHUP, on_exit);
- kill_pg(current->signal->tty_old_pgrp, SIGCONT, on_exit);
+ pid_t old_pgrp = current->signal->tty_old_pgrp;
+ if (old_pgrp) {
+ kill_pg(old_pgrp, SIGHUP, on_exit);
+ kill_pg(old_pgrp, SIGCONT, on_exit);
}
mutex_unlock(&tty_mutex);
unlock_kernel();
@@ -1505,19 +1509,29 @@ void disassociate_ctty(int on_exit)
kill_pg(tty_pgrp, SIGCONT, on_exit);
}
- /* Must lock changes to tty_old_pgrp */
- mutex_lock(&tty_mutex);
+ spin_lock_irq(¤t->sighand->siglock);
current->signal->tty_old_pgrp = 0;
- tty->session = 0;
- tty->pgrp = -1;
+ session = current->signal->session;
+ spin_unlock_irq(¤t->sighand->siglock);
+
+ mutex_lock(&tty_mutex);
+ /* It is possible that do_tty_hangup has free'd this tty */
+ tty = get_current_tty();
+ if (tty) {
+ tty->session = 0;
+ tty->pgrp = 0;
+ } else {
+#ifdef TTY_DEBUG_HANGUP
+ printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
+ " = NULL", tty);
+#endif
+ }
+ mutex_unlock(&tty_mutex);
/* Now clear signal->tty under the lock */
read_lock(&tasklist_lock);
- do_each_task_pid(current->signal->session, PIDTYPE_SID, p) {
- p->signal->tty = NULL;
- } while_each_task_pid(current->signal->session, PIDTYPE_SID, p);
+ session_clear_tty(session);
read_unlock(&tasklist_lock);
- mutex_unlock(&tty_mutex);
unlock_kernel();
}
@@ -2337,16 +2351,10 @@ static void release_dev(struct file * fi
* tty.
*/
if (tty_closing || o_tty_closing) {
- struct task_struct *p;
-
read_lock(&tasklist_lock);
- do_each_task_pid(tty->session, PIDTYPE_SID, p) {
- p->signal->tty = NULL;
- } while_each_task_pid(tty->session, PIDTYPE_SID, p);
+ session_clear_tty(tty->session);
if (o_tty)
- do_each_task_pid(o_tty->session, PIDTYPE_SID, p) {
- p->signal->tty = NULL;
- } while_each_task_pid(o_tty->session, PIDTYPE_SID, p);
+ session_clear_tty(o_tty->session);
read_unlock(&tasklist_lock);
}
@@ -2443,9 +2451,9 @@ static void release_dev(struct file * fi
* The termios state of a pty is reset on first open so that
* settings don't persist across reuse.
*
- * Locking: tty_mutex protects current->signal->tty, get_tty_driver and
- * init_dev work. tty->count should protect the rest.
- * task_lock is held to update task details for sessions
+ * Locking: tty_mutex protects tty, get_tty_driver and init_dev work.
+ * tty->count should protect the rest.
+ * ->siglock protects ->signal/->sighand
*/
static int tty_open(struct inode * inode, struct file * filp)
@@ -2467,12 +2475,13 @@ retry_open:
mutex_lock(&tty_mutex);
if (device == MKDEV(TTYAUX_MAJOR,0)) {
- if (!current->signal->tty) {
+ tty = get_current_tty();
+ if (!tty) {
mutex_unlock(&tty_mutex);
return -ENXIO;
}
- driver = current->signal->tty->driver;
- index = current->signal->tty->index;
+ driver = tty->driver;
+ index = tty->index;
filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
/* noctty = 1; */
goto got_driver;
@@ -2547,17 +2556,16 @@ got_driver:
filp->f_op = &tty_fops;
goto retry_open;
}
+
+ mutex_lock(&tty_mutex);
+ spin_lock_irq(¤t->sighand->siglock);
if (!noctty &&
current->signal->leader &&
!current->signal->tty &&
- tty->session == 0) {
- task_lock(current);
- current->signal->tty = tty;
- task_unlock(current);
- current->signal->tty_old_pgrp = 0;
- tty->session = current->signal->session;
- tty->pgrp = process_group(current);
- }
+ tty->session == 0)
+ __proc_set_tty(current, tty);
+ spin_unlock_irq(¤t->sighand->siglock);
+ mutex_unlock(&tty_mutex);
return 0;
}
@@ -2747,7 +2755,7 @@ static int tiocsti(struct tty_struct *tt
*
* Copies the kernel idea of the window size into the user buffer.
*
- * Locking: tty->termios_sem is taken to ensure the winsize data
+ * Locking: tty->termios_mutex is taken to ensure the winsize data
* is consistent.
*/
@@ -2774,8 +2782,8 @@ static int tiocgwinsz(struct tty_struct
* Locking:
* 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
+ * The tty->termios_mutex is used to ensure we don't double
+ * resize and get confused. Lock order - tty->termios_mutex before
* console sem
*/
@@ -2880,25 +2888,28 @@ static int fionbio(struct file *file, in
* leader to set this tty as the controlling tty for the session.
*
* Locking:
- * Takes tasklist lock internally to walk sessions
- * Takes task_lock() when updating signal->tty
* Takes tty_mutex() to protect tty instance
- *
+ * Takes tasklist_lock internally to walk sessions
+ * Takes ->siglock() when updating signal->tty
*/
static int tiocsctty(struct tty_struct *tty, int arg)
{
- struct task_struct *p;
-
+ int ret = 0;
if (current->signal->leader &&
(current->signal->session == tty->session))
- return 0;
+ return ret;
+
+ mutex_lock(&tty_mutex);
/*
* The process must be a session leader and
* not have a controlling tty already.
*/
- if (!current->signal->leader || current->signal->tty)
- return -EPERM;
+ if (!current->signal->leader || current->signal->tty) {
+ ret = -EPERM;
+ goto unlock;
+ }
+
if (tty->session > 0) {
/*
* This tty is already the controlling
@@ -2908,24 +2919,18 @@ static int tiocsctty(struct tty_struct *
/*
* Steal it away
*/
-
read_lock(&tasklist_lock);
- do_each_task_pid(tty->session, PIDTYPE_SID, p) {
- p->signal->tty = NULL;
- } while_each_task_pid(tty->session, PIDTYPE_SID, p);
+ session_clear_tty(tty->session);
read_unlock(&tasklist_lock);
- } else
- return -EPERM;
+ } else {
+ ret = -EPERM;
+ goto unlock;
+ }
}
- mutex_lock(&tty_mutex);
- task_lock(current);
- current->signal->tty = tty;
- task_unlock(current);
+ proc_set_tty(current, tty);
+unlock:
mutex_unlock(&tty_mutex);
- current->signal->tty_old_pgrp = 0;
- tty->session = current->signal->session;
- tty->pgrp = process_group(current);
- return 0;
+ return ret;
}
/**
@@ -2937,7 +2942,7 @@ static int tiocsctty(struct tty_struct *
* Obtain the process group of the tty. If there is no process group
* return an error.
*
- * Locking: none. Reference to ->signal->tty is safe.
+ * Locking: none. Reference to current->signal->tty is safe.
*/
static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
@@ -2995,7 +3000,7 @@ static int tiocspgrp(struct tty_struct *
* Obtain the session id of the tty. If there is no session
* return an error.
*
- * Locking: none. Reference to ->signal->tty is safe.
+ * Locking: none. Reference to current->signal->tty is safe.
*/
static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
@@ -3214,14 +3219,11 @@ int tty_ioctl(struct inode * inode, stru
clear_bit(TTY_EXCLUSIVE, &tty->flags);
return 0;
case TIOCNOTTY:
- /* FIXME: taks lock or tty_mutex ? */
if (current->signal->tty != tty)
return -ENOTTY;
if (current->signal->leader)
disassociate_ctty(0);
- task_lock(current);
- current->signal->tty = NULL;
- task_unlock(current);
+ proc_clear_tty(current);
return 0;
case TIOCSCTTY:
return tiocsctty(tty, arg);
@@ -3321,7 +3323,7 @@ static void __do_SAK(struct work_struct
if (!tty)
return;
- session = tty->session;
+ session = tty->session;
/* We don't want an ldisc switch during this */
disc = tty_ldisc_ref(tty);
@@ -3834,9 +3836,52 @@ int tty_unregister_driver(struct tty_dri
cdev_del(&driver->cdev);
return 0;
}
-
EXPORT_SYMBOL(tty_unregister_driver);
+dev_t tty_devnum(struct tty_struct *tty)
+{
+ return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
+}
+EXPORT_SYMBOL(tty_devnum);
+
+void proc_clear_tty(struct task_struct *p)
+{
+ spin_lock_irq(&p->sighand->siglock);
+ p->signal->tty = NULL;
+ spin_unlock_irq(&p->sighand->siglock);
+}
+EXPORT_SYMBOL(proc_clear_tty);
+
+void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
+{
+ if (tty) {
+ tty->session = tsk->signal->session;
+ tty->pgrp = process_group(tsk);
+ }
+ tsk->signal->tty = tty;
+ tsk->signal->tty_old_pgrp = 0;
+}
+
+void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
+{
+ spin_lock_irq(&tsk->sighand->siglock);
+ __proc_set_tty(tsk, tty);
+ spin_unlock_irq(&tsk->sighand->siglock);
+}
+
+struct tty_struct *get_current_tty(void)
+{
+ struct tty_struct *tty;
+ WARN_ON_ONCE(!mutex_is_locked(&tty_mutex));
+ tty = current->signal->tty;
+ /*
+ * session->tty can be changed/cleared from under us, make sure we
+ * issue the load. The obtained pointer, when not NULL, is valid as
+ * long as we hold tty_mutex.
+ */
+ barrier();
+ return tty;
+}
/*
* Initialize the console device. This is called *early*, so
diff -puN drivers/s390/char/fs3270.c~tty-signal-tty-locking drivers/s390/char/fs3270.c
--- a/drivers/s390/char/fs3270.c~tty-signal-tty-locking
+++ a/drivers/s390/char/fs3270.c
@@ -424,11 +424,15 @@ fs3270_open(struct inode *inode, struct
minor = iminor(filp->f_dentry->d_inode);
/* Check for minor 0 multiplexer. */
if (minor == 0) {
- if (!current->signal->tty)
+ struct tty_struct *tty;
+ mutex_lock(&tty_mutex);
+ tty = get_current_tty();
+ if (!tty || tty->driver->major != IBM_TTY3270_MAJOR) {
+ mutex_unlock(&tty_mutex);
return -ENODEV;
- if (current->signal->tty->driver->major != IBM_TTY3270_MAJOR)
- return -ENODEV;
- minor = current->signal->tty->index + RAW3270_FIRSTMINOR;
+ }
+ minor = tty->index + RAW3270_FIRSTMINOR;
+ mutex_unlock(&tty_mutex);
}
/* Check if some other program is already using fullscreen mode. */
fp = (struct fs3270 *) raw3270_find_view(&fs3270_fn, minor);
diff -puN fs/dquot.c~tty-signal-tty-locking fs/dquot.c
--- a/fs/dquot.c~tty-signal-tty-locking
+++ a/fs/dquot.c
@@ -828,6 +828,7 @@ static inline int need_print_warning(str
static void print_warning(struct dquot *dquot, const char warntype)
{
char *msg = NULL;
+ struct tty_struct *tty;
int flag = (warntype == BHARDWARN || warntype == BSOFTLONGWARN) ? DQ_BLKS_B :
((warntype == IHARDWARN || warntype == ISOFTLONGWARN) ? DQ_INODES_B : 0);
@@ -835,14 +836,15 @@ static void print_warning(struct dquot *
return;
mutex_lock(&tty_mutex);
- if (!current->signal->tty)
+ tty = get_current_tty();
+ if (!tty)
goto out_lock;
- tty_write_message(current->signal->tty, dquot->dq_sb->s_id);
+ tty_write_message(tty, dquot->dq_sb->s_id);
if (warntype == ISOFTWARN || warntype == BSOFTWARN)
- tty_write_message(current->signal->tty, ": warning, ");
+ tty_write_message(tty, ": warning, ");
else
- tty_write_message(current->signal->tty, ": write failed, ");
- tty_write_message(current->signal->tty, quotatypes[dquot->dq_type]);
+ tty_write_message(tty, ": write failed, ");
+ tty_write_message(tty, quotatypes[dquot->dq_type]);
switch (warntype) {
case IHARDWARN:
msg = " file limit reached.\r\n";
@@ -863,7 +865,7 @@ static void print_warning(struct dquot *
msg = " block quota exceeded.\r\n";
break;
}
- tty_write_message(current->signal->tty, msg);
+ tty_write_message(tty, msg);
out_lock:
mutex_unlock(&tty_mutex);
}
diff -puN fs/open.c~tty-signal-tty-locking fs/open.c
--- a/fs/open.c~tty-signal-tty-locking
+++ a/fs/open.c
@@ -1087,6 +1087,7 @@ EXPORT_SYMBOL(sys_close);
asmlinkage long sys_vhangup(void)
{
if (capable(CAP_SYS_TTY_CONFIG)) {
+ /* XXX: this needs locking */
tty_vhangup(current->signal->tty);
return 0;
}
diff -puN include/linux/tty.h~tty-signal-tty-locking include/linux/tty.h
--- a/include/linux/tty.h~tty-signal-tty-locking
+++ a/include/linux/tty.h
@@ -309,6 +309,12 @@ extern void tty_ldisc_flush(struct tty_s
extern int tty_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg);
+extern dev_t tty_devnum(struct tty_struct *tty);
+extern void proc_clear_tty(struct task_struct *p);
+extern void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
+extern void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
+extern struct tty_struct *get_current_tty(void);
+
extern struct mutex tty_mutex;
/* n_tty.c */
@@ -335,10 +341,5 @@ extern void console_print(const char *);
extern int vt_ioctl(struct tty_struct *tty, struct file * file,
unsigned int cmd, unsigned long arg);
-static inline dev_t tty_devnum(struct tty_struct *tty)
-{
- return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
-}
-
#endif /* __KERNEL__ */
#endif
diff -puN kernel/acct.c~tty-signal-tty-locking kernel/acct.c
--- a/kernel/acct.c~tty-signal-tty-locking
+++ a/kernel/acct.c
@@ -428,6 +428,7 @@ static void do_acct_process(struct file
u64 elapsed;
u64 run_time;
struct timespec uptime;
+ struct tty_struct *tty;
/*
* First check to see if there is enough free_space to continue
@@ -485,12 +486,8 @@ static void do_acct_process(struct file
#endif
mutex_lock(&tty_mutex);
- /* FIXME: Whoever is responsible for current->signal locking needs
- to use the same locking all over the kernel and document it */
- read_lock(&tasklist_lock);
- ac.ac_tty = current->signal->tty ?
- old_encode_dev(tty_devnum(current->signal->tty)) : 0;
- read_unlock(&tasklist_lock);
+ tty = get_current_tty();
+ ac.ac_tty = tty ? old_encode_dev(tty_devnum(tty)) : 0;
mutex_unlock(&tty_mutex);
spin_lock_irq(¤t->sighand->siglock);
diff -puN kernel/auditsc.c~tty-signal-tty-locking kernel/auditsc.c
--- a/kernel/auditsc.c~tty-signal-tty-locking
+++ a/kernel/auditsc.c
@@ -826,10 +826,12 @@ static void audit_log_exit(struct audit_
context->return_code);
mutex_lock(&tty_mutex);
+ read_lock(&tasklist_lock);
if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name)
tty = tsk->signal->tty->name;
else
tty = "(none)";
+ read_unlock(&tasklist_lock);
audit_log_format(ab,
" a0=%lx a1=%lx a2=%lx a3=%lx items=%d"
" ppid=%d pid=%d auid=%u uid=%u gid=%u"
diff -puN kernel/exit.c~tty-signal-tty-locking kernel/exit.c
--- a/kernel/exit.c~tty-signal-tty-locking
+++ a/kernel/exit.c
@@ -384,9 +384,7 @@ void daemonize(const char *name, ...)
exit_mm(current);
set_special_pids(1, 1);
- mutex_lock(&tty_mutex);
- current->signal->tty = NULL;
- mutex_unlock(&tty_mutex);
+ proc_clear_tty(current);
/* Block and flush all signals */
sigfillset(&blocked);
diff -puN kernel/sys.c~tty-signal-tty-locking kernel/sys.c
--- a/kernel/sys.c~tty-signal-tty-locking
+++ a/kernel/sys.c
@@ -1484,7 +1484,6 @@ asmlinkage long sys_setsid(void)
pid_t session;
int err = -EPERM;
- mutex_lock(&tty_mutex);
write_lock_irq(&tasklist_lock);
/* Fail if I am already a session leader */
@@ -1504,12 +1503,15 @@ asmlinkage long sys_setsid(void)
group_leader->signal->leader = 1;
__set_special_pids(session, session);
+
+ spin_lock(&group_leader->sighand->siglock);
group_leader->signal->tty = NULL;
group_leader->signal->tty_old_pgrp = 0;
+ spin_unlock(&group_leader->sighand->siglock);
+
err = process_group(group_leader);
out:
write_unlock_irq(&tasklist_lock);
- mutex_unlock(&tty_mutex);
return err;
}
diff -puN security/selinux/hooks.c~tty-signal-tty-locking security/selinux/hooks.c
--- a/security/selinux/hooks.c~tty-signal-tty-locking
+++ a/security/selinux/hooks.c
@@ -1695,9 +1695,10 @@ static inline void flush_unauthorized_fi
struct tty_struct *tty;
struct fdtable *fdt;
long j = -1;
+ int drop_tty = 0;
mutex_lock(&tty_mutex);
- tty = current->signal->tty;
+ tty = get_current_tty();
if (tty) {
file_list_lock();
file = list_entry(tty->tty_files.next, typeof(*file), f_u.fu_list);
@@ -1710,12 +1711,14 @@ static inline void flush_unauthorized_fi
struct inode *inode = file->f_dentry->d_inode;
if (inode_has_perm(current, inode,
FILE__READ | FILE__WRITE, NULL)) {
- /* Reset controlling tty. */
- current->signal->tty = NULL;
- current->signal->tty_old_pgrp = 0;
+ drop_tty = 1;
}
}
file_list_unlock();
+
+ /* Reset controlling tty. */
+ if (drop_tty)
+ proc_set_tty(current, NULL);
}
mutex_unlock(&tty_mutex);
_
Patches currently in -mm which might be from a.p.zijlstra@xxxxxxxxx are
origin.patch
tty-signal-tty-locking.patch
do_task_stat-dont-take-tty_mutex.patch
do_acct_process-dont-take-tty_mutex.patch
sys_unshare-remove-a-broken-clone_sighand-code.patch
remove-the-old-bd_mutex-lockdep-annotation.patch
new-bd_mutex-lockdep-annotation.patch
remove-lock_key-approach-to-managing-nested-bd_mutex-locks.patch
simplify-some-aspects-of-bd_mutex-nesting.patch
use-mutex_lock_nested-for-bd_mutex-to-avoid-lockdep-warning.patch
avoid-lockdep-warning-in-md.patch
bdev-fix-bd_part_count-leak.patch
lockdep-annotate-nfsd4-recover-code.patch
-
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