The patch titled
ptrace_check_attach: remove unneeded ->signal != NULL check
has been added to the -mm tree. Its filename is
ptrace_check_attach-remove-unneeded-signal-=-null-check.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: ptrace_check_attach: remove unneeded ->signal != NULL check
From: Oleg Nesterov <oleg@xxxxxxxxxx>
It is not possible to see the PT_PTRACED task without ->signal/sighand under
tasklist_lock, release_task() does ptrace_unlink() first. If the task was
already released before, ptrace_attach() can't succeed and set PT_PTRACED.
Remove this check.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/ptrace.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff -puN kernel/ptrace.c~ptrace_check_attach-remove-unneeded-signal-=-null-check kernel/ptrace.c
--- a/kernel/ptrace.c~ptrace_check_attach-remove-unneeded-signal-=-null-check
+++ a/kernel/ptrace.c
@@ -99,9 +99,12 @@ int ptrace_check_attach(struct task_stru
* be changed by us so it's not changing right after this.
*/
read_lock(&tasklist_lock);
- if ((child->ptrace & PT_PTRACED) && child->parent == current &&
- child->signal != NULL) {
+ if ((child->ptrace & PT_PTRACED) && child->parent == current) {
ret = 0;
+ /*
+ * child->sighand can't be NULL, release_task()
+ * does ptrace_unlink() before __exit_signal().
+ */
spin_lock_irq(&child->sighand->siglock);
if (is_task_stopped(child))
__set_task_state(child, TASK_TRACED);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
wait_task_stopped-dont-use-task_pid_nr_ns-lockless.patch
proc-remove-races-from-proc_id_readdir.patch
wait_task_stopped-pass-correct-exit_code-to.patch
use-__set_task_state-for-traced-stopped-tasks.patch
add-task_wakekill.patch
do_wait-remove-one-else-if-branch.patch
proc-implement-proc_single_file_operations.patch
proc-rewrite-do_task_stat-to-correctly-handle-pid-namespaces.patch
proc-seqfile-convert-proc_pid_statm.patch
proc-proper-pidns-handling-for-proc-self.patch
proc-fix-the-threaded-proc-self.patch
kill-pt_attached.patch
kill-my_ptrace_child.patch
ptrace_check_attach-remove-unneeded-signal-=-null-check.patch
-
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