CVE-2026-46259

In the Linux kernel, the following vulnerability has been resolved:

procfs: fix missing RCU protection when reading real_parent in do_task_stat()

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.