diff options
| -rw-r--r-- | kernel/ptrace.c | 59 |
1 files changed, 13 insertions, 46 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 12e21a949db..38fdfea1a15 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -167,7 +167,6 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode) int ptrace_attach(struct task_struct *task) { int retval; - unsigned long flags; audit_ptrace(task); @@ -185,34 +184,19 @@ int ptrace_attach(struct task_struct *task) retval = mutex_lock_interruptible(&task->cred_guard_mutex); if (retval < 0) goto out; -repeat: - /* - * Nasty, nasty. - * - * We want to hold both the task-lock and the - * tasklist_lock for writing at the same time. - * But that's against the rules (tasklist_lock - * is taken for reading by interrupts on other - * cpu's that may have task_lock). - */ - task_lock(task); - if (!write_trylock_irqsave(&tasklist_lock, flags)) { - task_unlock(task); - do { - cpu_relax(); - } while (!write_can_lock(&tasklist_lock)); - goto repeat; - } + task_lock(task); retval = __ptrace_may_access(task, PTRACE_MODE_ATTACH); + task_unlock(task); if (retval) - goto bad; + goto unlock_creds; + write_lock_irq(&tasklist_lock); retval = -EPERM; if (unlikely(task->exit_state)) - goto bad; + goto unlock_tasklist; if (task->ptrace) - goto bad; + goto unlock_tasklist; task->ptrace = PT_PTRACED; if (capable(CAP_SYS_PTRACE)) @@ -222,9 +206,9 @@ repeat: send_sig_info(SIGSTOP, SEND_SIG_FORCED, task); retval = 0; -bad: - write_unlock_irqrestore(&tasklist_lock, flags); - task_unlock(task); +unlock_tasklist: + write_unlock_irq(&tasklist_lock); +unlock_creds: mutex_unlock(&task->cred_guard_mutex); out: return retval; @@ -240,26 +224,10 @@ int ptrace_traceme(void) { int ret = -EPERM; - /* - * Are we already being traced? - */ -repeat: - task_lock(current); + write_lock_irq(&tasklist_lock); + /* Are we already being traced? */ if (!current->ptrace) { - /* - * See ptrace_attach() comments about the locking here. - */ - unsigned long flags; - if (!write_trylock_irqsave(&tasklist_lock, flags)) { - task_unlock(current); - do { - cpu_relax(); - } while (!write_can_lock(&tasklist_lock)); - goto repeat; - } - ret = security_ptrace_traceme(current->parent); - /* * Check PF_EXITING to ensure ->real_parent has not passed * exit_ptrace(). Otherwise we don't report the error but @@ -269,10 +237,9 @@ repeat: current->ptrace = PT_PTRACED; __ptrace_link(current, current->real_parent); } - - write_unlock_irqrestore(&tasklist_lock, flags); } - task_unlock(current); + write_unlock_irq(&tasklist_lock); + return ret; } |