The patch titled
Subject: sched_show_task: fix unsafe usage of ->real_parent
has been added to the -mm tree. Its filename is
sched_show_task-fix-unsafe-usage-of-real_parent.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/sched_show_task-fix-unsafe-usage-of-real_parent.patch
echo and later at
echo http://ozlabs.org/~akpm/mmotm/broken-out/sched_show_task-fix-unsafe-usage-of-real_parent.patch
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: sched_show_task: fix unsafe usage of ->real_parent
rcu_read_lock() can not protect p->real_parent if release_task(p) was
already called, change sched_show_task() to check pis_alive() like other
users do.
Note: we need some helpers to cleanup the code like this. And it seems
that that the usage of cpu_curr(cpu) in dump_cpu_task() is not safe too.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Aaron Tomlin <atomlin@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>,
Cc: Sterling Alexander <stalexan@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff -puN kernel/sched/core.c~sched_show_task-fix-unsafe-usage-of-real_parent kernel/sched/core.c
--- a/kernel/sched/core.c~sched_show_task-fix-unsafe-usage-of-real_parent
+++ a/kernel/sched/core.c
@@ -4572,8 +4572,10 @@ void sched_show_task(struct task_struct
#ifdef CONFIG_DEBUG_STACK_USAGE
free = stack_not_used(p);
#endif
+ ppid = 0;
rcu_read_lock();
- ppid = task_pid_nr(rcu_dereference(p->real_parent));
+ if (pid_alive(p))
+ ppid = task_pid_nr(rcu_dereference(p->real_parent));
rcu_read_unlock();
printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free,
task_pid_nr(p), ppid,
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
mmfs-introduce-helpers-around-the-i_mmap_mutex.patch
mm-use-new-helper-functions-around-the-i_mmap_mutex.patch
mm-convert-i_mmap_mutex-to-rwsem.patch
mm-rmap-share-the-i_mmap_rwsem.patch
uprobes-share-the-i_mmap_rwsem.patch
mm-xip-share-the-i_mmap_rwsem.patch
mm-memory-failure-share-the-i_mmap_rwsem.patch
mm-nommu-share-the-i_mmap_rwsem.patch
mm-memoryc-share-the-i_mmap_rwsem.patch
proc-task_state-read-cred-group_info-outside-of-task_lock.patch
proc-task_state-deuglify-the-max_fds-calculation.patch
proc-task_state-move-the-main-seq_printf-outside-of-rcu_read_lock.patch
proc-task_state-ptrace_parent-doesnt-need-pid_alive-check.patch
sched_show_task-fix-unsafe-usage-of-real_parent.patch
exit-reparent-use-ptrace_entry-rather-than-sibling-for-exit_dead-tasks.patch
exit-reparent-cleanup-the-changing-of-parent.patch
exit-reparent-cleanup-the-usage-of-reparent_leader.patch
exit-ptrace-shift-reap-dead-code-from-exit_ptrace-to-forget_original_parent.patch
usermodehelper-dont-use-clone_vfork-for-____call_usermodehelper.patch
usermodehelper-kill-the-kmod_thread_locker-logic.patch
linux-next.patch
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