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audit: Call tty_audit_push_task() outside preempt disabled

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While auditing all tasklist_lock read_lock sites I stumbled over the
following call chain:

audit_prepare_user_tty()
  read_lock(&tasklist_lock);
  tty_audit_push_task();
     mutex_lock(&buf->mutex);

     --> buf->mutex is locked with preemption disabled.

Solve this by acquiring a reference to the task struct under
rcu_read_lock and call tty_audit_push_task outside of the preempt
disabled region.

Move all code which needs to be protected by sighand lock into
tty_audit_push_task() and use lock/unlock_sighand as we do not hold
tasklist_lock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Thomas Gleixner 2009-12-09 14:19:31 +00:00 • committed by Al Viro
commit 3c80fe4ac9
3 changed files with 42 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

9
include/linux/tty.h
View file

@ -541,8 +541,8 @@ extern void tty_audit_exit(void);
extern void tty_audit_fork(struct signal_struct *sig);
extern void tty_audit_tiocsti(struct tty_struct *tty, char ch);
extern void tty_audit_push(struct tty_struct *tty);
extern void tty_audit_push_task(struct task_struct *tsk,
uid_t loginuid, u32 sessionid);
extern int tty_audit_push_task(struct task_struct *tsk,
uid_t loginuid, u32 sessionid);
#else
static inline void tty_audit_add_data(struct tty_struct *tty,
unsigned char *data, size_t size)
@ -560,9 +560,10 @@ static inline void tty_audit_fork(struct signal_struct *sig)
static inline void tty_audit_push(struct tty_struct *tty)
{
}
static inline void tty_audit_push_task(struct task_struct *tsk,
uid_t loginuid, u32 sessionid)
static inline int tty_audit_push_task(struct task_struct *tsk,
uid_t loginuid, u32 sessionid)
{
return 0;
}
#endif