Jinliang Zheng 73ec7c9660 procfs: fix missing RCU protection when reading real_parent in do_task_stat() ...

[ Upstream commit 76149d5350 ]

When reading /proc/[pid]/stat, do_task_stat() accesses task->real_parent
without proper RCU protection, which leads to:

  cpu 0                               cpu 1
  -----                               -----
  do_task_stat
    var = task->real_parent
                                      release_task
                                        call_rcu(delayed_put_task_struct)
    task_tgid_nr_ns(var)
      rcu_read_lock   <--- Too late to protect task->real_parent!
      task_pid_ptr    <--- UAF!
      rcu_read_unlock

This patch uses task_ppid_nr_ns() instead of task_tgid_nr_ns() to add
proper RCU protection for accessing task->real_parent.

Link: https://lkml.kernel.org/r/20260128083007.3173016-1-alexjlzheng@tencent.com
Fixes: 06fffb1267 ("do_task_stat: don't take rcu_read_lock()")
Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: ruippan <ruippan@tencent.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2026-03-04 07:20:11 -05:00

..

array.c

…

base.c

…

bootconfig.c

…

cmdline.c

…

consoles.c

…

cpuinfo.c

…

devices.c

…

fd.c

…

fd.h

…

generic.c

…

inode.c

…

internal.h

…

interrupts.c

…

Kconfig

…

kcore.c

…

kmsg.c

…

loadavg.c

…

Makefile

…

meminfo.c

…

namespaces.c

…

nommu.c

…

page.c

…

proc_net.c

…

proc_sysctl.c

…

proc_tty.c

…

root.c

…

self.c

…

softirqs.c

…

stat.c

…

task_mmu.c

…

task_nommu.c

…

thread_self.c

…

uptime.c

…

util.c

…

version.c

…

vmcore.c

…