The patch titled
ptrace_stop: fix the race with ptrace detach+attach
has been added to the -mm tree. Its filename is
ptrace_stop-fix-the-race-with-ptrace-detachattach.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_stop: fix the race with ptrace detach+attach
From: Oleg Nesterov <oleg@xxxxxxxxxx>
If the tracer went away (may_ptrace_stop() failed), ptrace_stop() drops
tasklist and then changes the ->state from TASK_TRACED to TASK_RUNNING.
This can fool another tracer which attaches to us in between. Change the
->state under tasklist_lock to ensure that ptrace_check_attach() can't wrongly
succeed. Also, remove the unnecessary mb().
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland Dreier <rolandd@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN kernel/signal.c~ptrace_stop-fix-the-race-with-ptrace-detachattach kernel/signal.c
--- a/kernel/signal.c~ptrace_stop-fix-the-race-with-ptrace-detachattach
+++ a/kernel/signal.c
@@ -1628,11 +1628,11 @@ static void ptrace_stop(int exit_code, i
} else {
/*
* By the time we got the lock, our tracer went away.
- * Don't stop here.
+ * Don't drop the lock yet, another tracer may come.
*/
- read_unlock(&tasklist_lock);
- set_current_state(TASK_RUNNING);
+ __set_current_state(TASK_RUNNING);
current->exit_code = nostop_code;
+ read_unlock(&tasklist_lock);
}
/*
_
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
ptrace_stop-fix-the-race-with-ptrace-detachattach.patch
wait_task_stopped-simplify-and-fix-races-with-sigcont-sigkill-untrace.patch
do_wait-factor-out-retval-=-0-checks.patch
-
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