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-rw-r--r--kernel/ptrace.c59
1 files changed, 13 insertions, 46 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 12e21a949db1..38fdfea1a15a 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;
}