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[PATCH] coredump: kill ptrace related stuff

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With this patch zap_process() sets SIGNAL_GROUP_EXIT while sending SIGKILL to
the thread group.  This means that a TASK_TRACED task

	1. Will be awakened by signal_wake_up(1)

	2. Can't sleep again via ptrace_notify()

	3. Can't go to do_signal_stop() after return
	   from ptrace_stop() in get_signal_to_deliver()

So we can remove all ptrace related stuff from coredump path.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Oleg Nesterov 2006-06-26 00:26:07 -07:00 • committed by Linus Torvalds
parent 281de339ce
commit d5f70c00ad
4 changed files with 37 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

35
kernel/signal.c
View file

@ -1531,6 +1531,35 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, int why)
spin_unlock_irqrestore(&sighand->siglock, flags);
}
static inline int may_ptrace_stop(void)
{
if (!likely(current->ptrace & PT_PTRACED))
return 0;
if (unlikely(current->parent == current->real_parent &&
(current->ptrace & PT_ATTACHED)))
return 0;
if (unlikely(current->signal == current->parent->signal) &&
unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))
return 0;
/*
* Are we in the middle of do_coredump?
* If so and our tracer is also part of the coredump stopping
* is a deadlock situation, and pointless because our tracer
* is dead so don't allow us to stop.
* If SIGKILL was already sent before the caller unlocked
* ->siglock we must see ->core_waiters != 0. Otherwise it
* is safe to enter schedule().
*/
if (unlikely(current->mm->core_waiters) &&
unlikely(current->mm == current->parent->mm))
return 0;
return 1;
}
/*
* This must be called with current->sighand->siglock held.
*
@ -1559,11 +1588,7 @@ static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info)
spin_unlock_irq(&current->sighand->siglock);
try_to_freeze();
read_lock(&tasklist_lock);
if (likely(current->ptrace & PT_PTRACED) &&
likely(current->parent != current->real_parent ||
!(current->ptrace & PT_ATTACHED)) &&
(likely(current->parent->signal != current->signal) ||
!unlikely(current->signal->flags & SIGNAL_GROUP_EXIT))) {
if (may_ptrace_stop()) {
do_notify_parent_cldstop(current, CLD_TRAPPED);
read_unlock(&tasklist_lock);
schedule();