Commit 3e7cd6c4 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds

[PATCH] pid: replace is_orphaned_pgrp with is_current_pgrp_orphaned

Every call to is_orphaned_pgrp passed in process_group(current) which is racy
with respect to another thread changing our process group.  It didn't bite us
because we were dealing with integers and the worse we would get would be a
stale answer.

In switching the checks to use struct pid to be a little more efficient and
prepare the way for pid namespaces this race became apparent.

So I simplified the calls to the more specialized is_current_pgrp_orphaned so
I didn't have to worry about making logic changes to avoid the race.
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0475ac08
...@@ -1188,7 +1188,7 @@ static int job_control(struct tty_struct *tty, struct file *file) ...@@ -1188,7 +1188,7 @@ static int job_control(struct tty_struct *tty, struct file *file)
printk("read_chan: tty->pgrp <= 0!\n"); printk("read_chan: tty->pgrp <= 0!\n");
else if (process_group(current) != tty->pgrp) { else if (process_group(current) != tty->pgrp) {
if (is_ignored(SIGTTIN) || if (is_ignored(SIGTTIN) ||
is_orphaned_pgrp(process_group(current))) is_current_pgrp_orphaned())
return -EIO; return -EIO;
kill_pg(process_group(current), SIGTTIN, 1); kill_pg(process_group(current), SIGTTIN, 1);
return -ERESTARTSYS; return -ERESTARTSYS;
......
...@@ -1118,7 +1118,7 @@ int tty_check_change(struct tty_struct * tty) ...@@ -1118,7 +1118,7 @@ int tty_check_change(struct tty_struct * tty)
return 0; return 0;
if (is_ignored(SIGTTOU)) if (is_ignored(SIGTTOU))
return 0; return 0;
if (is_orphaned_pgrp(process_group(current))) if (is_current_pgrp_orphaned())
return -EIO; return -EIO;
(void) kill_pg(process_group(current), SIGTTOU, 1); (void) kill_pg(process_group(current), SIGTTOU, 1);
return -ERESTARTSYS; return -ERESTARTSYS;
......
...@@ -303,7 +303,7 @@ extern int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp, ...@@ -303,7 +303,7 @@ extern int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp,
int buflen); int buflen);
extern void tty_write_message(struct tty_struct *tty, char *msg); extern void tty_write_message(struct tty_struct *tty, char *msg);
extern int is_orphaned_pgrp(int pgrp); extern int is_current_pgrp_orphaned(void);
extern int is_ignored(int sig); extern int is_ignored(int sig);
extern int tty_signal(int sig, struct tty_struct *tty); extern int tty_signal(int sig, struct tty_struct *tty);
extern void tty_hangup(struct tty_struct * tty); extern void tty_hangup(struct tty_struct * tty);
......
...@@ -229,12 +229,12 @@ static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignor ...@@ -229,12 +229,12 @@ static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignor
return ret; /* (sighing) "Often!" */ return ret; /* (sighing) "Often!" */
} }
int is_orphaned_pgrp(int pgrp) int is_current_pgrp_orphaned(void)
{ {
int retval; int retval;
read_lock(&tasklist_lock); read_lock(&tasklist_lock);
retval = will_become_orphaned_pgrp(find_pid(pgrp), NULL); retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
read_unlock(&tasklist_lock); read_unlock(&tasklist_lock);
return retval; return retval;
......
...@@ -1909,7 +1909,7 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, ...@@ -1909,7 +1909,7 @@ int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
/* signals can be posted during this window */ /* signals can be posted during this window */
if (is_orphaned_pgrp(process_group(current))) if (is_current_pgrp_orphaned())
goto relock; goto relock;
spin_lock_irq(&current->sighand->siglock); spin_lock_irq(&current->sighand->siglock);
......
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