linux/kernel/rcu
Paul E. McKenney f747c7e15d rcu-tasks: Enclose task-list scan in rcu_read_lock()
The rcu_tasks_trace_postgp() function uses for_each_process_thread()
to scan the task list without the benefit of RCU read-side protection,
which can result in use-after-free errors on task_struct structures.
This error was missed because the TRACE01 rcutorture scenario enables
lockdep, but also builds with CONFIG_PREEMPT_NONE=y.  In this situation,
preemption is disabled everywhere, so lockdep thinks everywhere can
be a legitimate RCU reader.  This commit therefore adds the needed
rcu_read_lock() and rcu_read_unlock().

Note that this bug can occur only after an RCU Tasks Trace CPU stall
warning, which by default only happens after a grace period has extended
for ten minutes (yes, not a typo, minutes).

Fixes: 4593e772b5 ("rcu-tasks: Add stall warnings for RCU Tasks Trace")
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: <bpf@vger.kernel.org>
Cc: <stable@vger.kernel.org> # 5.7.x
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-09-16 16:32:38 -07:00
..
Kconfig rcu-tasks: Add Kconfig option to mediate smp_mb() vs. IPI 2020-04-27 11:03:52 -07:00
Kconfig.debug refperf: Rename RCU_REF_PERF_TEST to RCU_REF_SCALE_TEST 2020-06-29 12:00:46 -07:00
Makefile refperf: Rename refperf.c to refscale.c and change internal names 2020-06-29 12:00:46 -07:00
rcu_segcblist.c rcu: Remove dead code from rcu_segcblist_insert_pend_cbs() 2020-02-20 15:58:23 -08:00
rcu_segcblist.h rcu: Remove kfree_rcu() special casing and lazy-callback handling 2020-01-24 10:24:31 -08:00
rcu.h Merge branches 'fixes.2020.04.27a', 'kfree_rcu.2020.04.27a', 'rcu-tasks.2020.04.27a', 'stall.2020.04.27a' and 'torture.2020.05.07a' into HEAD 2020-05-07 10:18:32 -07:00
rcuperf.c This tree adds the sched_set_fifo*() encapsulation APIs to remove 2020-08-06 11:55:43 -07:00
rcutorture.c This tree adds the sched_set_fifo*() encapsulation APIs to remove 2020-08-06 11:55:43 -07:00
refscale.c refperf: Rename refperf.c to refscale.c and change internal names 2020-06-29 12:00:46 -07:00
srcutiny.c rcu: Use CONFIG_PREEMPTION where appropriate 2019-12-09 12:37:51 -08:00
srcutree.c srcu: Avoid local_irq_save() before acquiring spinlock_t 2020-06-29 12:01:22 -07:00
sync.c rcu/sync: Simplify the state machine 2019-05-28 09:05:23 -07:00
tasks.h rcu-tasks: Enclose task-list scan in rcu_read_lock() 2020-09-16 16:32:38 -07:00
tiny.c rcu: Rename *_kfree_callback/*_kfree_rcu_offset/kfree_call_* 2020-06-29 11:59:25 -07:00
tree_exp.h rcu: Expedited grace-period sleeps to idle priority 2020-06-29 11:58:50 -07:00
tree_plugin.h rcu: No-CBs-related sleeps to idle priority 2020-06-29 11:58:50 -07:00
tree_stall.h Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD 2020-06-29 12:03:15 -07:00
tree.c rcu: kasan: record and print call_rcu() call stack 2020-08-07 11:33:28 -07:00
tree.h rcu: grpnum just records group number 2020-06-29 11:58:51 -07:00
update.c Merge branches 'doc.2020.06.29a', 'fixes.2020.06.29a', 'kfree_rcu.2020.06.29a', 'rcu-tasks.2020.06.29a', 'scale.2020.06.29a', 'srcu.2020.06.29a' and 'torture.2020.06.29a' into HEAD 2020-06-29 12:03:15 -07:00