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dc487ccdbe
[ Upstream commit 76149d53502cf17ef3ae454ff384551236fba867 ]
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>
Signed-off-by: Ulrich Hecht <uli@kernel.org>