The patch titled
coredump-kill-ptrace-related-stuff-fix
has been removed from the -mm tree. Its filename is
coredump-kill-ptrace-related-stuff-fix.patch
This patch was dropped because it was folded into coredump-kill-ptrace-related-stuff.patch
------------------------------------------------------
Subject: coredump-kill-ptrace-related-stuff-fix
From: Oleg Nesterov <oleg@xxxxxxxxxx>
1. Roland McGrath pointed out that SIGNAL_GROUP_EXIT can't
prevent the task from going to ptrace_stop() and schedule
in TASK_TRACED state.
As Eric W. Biederman suggested, ptrace_stop() should check
->core_waiters.
2. This patch killed 'if (child->ptrace)' check in ptrace_detach()
because that check was added to protect against ptrace_detach()
vs zap_threads() race.
However, the check is still needed: de_thread() can release the
task after ptrace_check_attach() succeeded.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/ptrace.c | 4 +++-
kernel/signal.c | 35 ++++++++++++++++++++++++++++++-----
2 files changed, 33 insertions(+), 6 deletions(-)
diff -puN kernel/ptrace.c~coredump-kill-ptrace-related-stuff-fix kernel/ptrace.c
--- devel/kernel/ptrace.c~coredump-kill-ptrace-related-stuff-fix 2006-05-14 08:08:54.000000000 -0700
+++ devel-akpm/kernel/ptrace.c 2006-05-14 08:08:54.000000000 -0700
@@ -233,7 +233,9 @@ int ptrace_detach(struct task_struct *ch
ptrace_disable(child);
write_lock_irq(&tasklist_lock);
- __ptrace_detach(child, data);
+ /* protect against de_thread()->release_task() */
+ if (child->ptrace)
+ __ptrace_detach(child, data);
write_unlock_irq(&tasklist_lock);
return 0;
diff -puN kernel/signal.c~coredump-kill-ptrace-related-stuff-fix kernel/signal.c
--- devel/kernel/signal.c~coredump-kill-ptrace-related-stuff-fix 2006-05-14 08:08:54.000000000 -0700
+++ devel-akpm/kernel/signal.c 2006-05-14 08:08:54.000000000 -0700
@@ -1531,6 +1531,35 @@ static void do_notify_parent_cldstop(str
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, i
spin_unlock_irq(¤t->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();
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
proc-remove-tasklist_lock-from-proc_pid_readdir-simply-fix-first_tgid.patch
proc-dont-lock-task_structs-indefinitely.patch
simplify-fix-first_tid.patch
cleanup-next_tid.patch
de_thread-fix-lockless-do_each_thread.patch
coredump-optimize-mm-users-traversal.patch
coredump-speedup-sigkill-sending.patch
coredump-kill-ptrace-related-stuff.patch
coredump-kill-ptrace-related-stuff-fix.patch
coredump-dont-take-tasklist_lock.patch
coredump-some-code-relocations.patch
coredump-shutdown-current-process-first.patch
coredump-copy_process-dont-check-signal_group_exit.patch
-
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