Files
linux/kernel
Cheng-Yang Chou 2008fb2573 sched_ext: Fix slab-out-of-bounds in scx_alloc_and_add_sched()
ancestors[] is a flexible array member that needs level + 1 slots to
hold all ancestors including self (indices 0..level), but kzalloc_flex()
only allocates `level` slots:

  sch = kzalloc_flex(*sch, ancestors, level);
  ...
  sch->ancestors[level] = sch;  /* one past the end */

For the root scheduler (level = 0), zero slots are allocated and
ancestors[0] is written immediately past the end of the object.

KASAN reports:

  BUG: KASAN: slab-out-of-bounds in scx_alloc_and_add_sched+0x1c17/0x1d10
  Write of size 8 at addr ffff888066b56538 by task scx_enable_help/667

  The buggy address is located 0 bytes to the right of
   allocated 1336-byte region [ffff888066b56000, ffff888066b56538)

Fix by passing level + 1 to kzalloc_flex().

Tested with vng + scx_lavd, KASAN no longer triggers.

Fixes: ebeca1f930 ("sched_ext: Introduce cgroup sub-sched support")
Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2026-03-16 07:55:50 -10:00
..
2026-03-05 18:15:58 -10:00
2026-01-05 16:43:34 +01:00
2025-11-04 08:30:50 +01:00
2025-10-29 10:29:54 +01:00
2026-01-26 19:07:13 -08:00