linux/mm/kasan
Juntong Deng a5989d4ed4 kasan: improve free meta storage in Generic KASAN
Currently free meta can only be stored in object if the object is not
smaller than free meta.

After the improvement, when the object is smaller than free meta and SLUB
DEBUG is not enabled, it is possible to store part of the free meta in the
object, reducing the increased size of the red zone.

Example:

free meta size: 16 bytes
alloc meta size: 16 bytes
object size: 8 bytes
optimal redzone size (object_size <= 64): 16 bytes

Before improvement:
actual redzone size = alloc meta size + free meta size = 32 bytes

After improvement:
actual redzone size = alloc meta size + (free meta size - object size)
                    = 24 bytes

[juntong.deng@outlook.com: make kasan_metadata_size() adapt to the improved free meta storage]
  Link: https://lkml.kernel.org/r/VI1P193MB0752675D6E0A2D16CE656F8299BAA@VI1P193MB0752.EURP193.PROD.OUTLOOK.COM
Link: https://lkml.kernel.org/r/VI1P193MB0752DE2CCD9046B5FED0AA8E99B5A@VI1P193MB0752.EURP193.PROD.OUTLOOK.COM
Signed-off-by: Juntong Deng <juntong.deng@outlook.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-12-10 16:51:50 -08:00
..
common.c kasan: use stack_depot_put for Generic mode 2023-12-10 16:51:48 -08:00
generic.c kasan: improve free meta storage in Generic KASAN 2023-12-10 16:51:50 -08:00
hw_tags.c kasan: hw_tags: avoid invalid virt_to_page() 2023-05-02 17:23:27 -07:00
init.c kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate process 2023-09-06 22:54:16 +08:00
kasan_test_module.c kasan: unify printk prefixes 2023-10-18 14:34:15 -07:00
kasan_test.c mm: delete checks for xor_unlock_is_negative_byte() 2023-10-18 14:34:17 -07:00
kasan.h lib/stackdepot, kasan: add flags to __stack_depot_save and rename 2023-12-10 16:51:46 -08:00
Makefile kasan: test: fix test for new meminstrinsic instrumentation 2023-03-02 21:54:22 -08:00
quarantine.c kasan: use stack_depot_put for Generic mode 2023-12-10 16:51:48 -08:00
report_generic.c kasan: unify printk prefixes 2023-10-18 14:34:15 -07:00
report_hw_tags.c kasan: use internal prototypes matching gcc-13 builtins 2023-06-09 16:25:19 -07:00
report_sw_tags.c kasan: use internal prototypes matching gcc-13 builtins 2023-06-09 16:25:19 -07:00
report_tags.c kasan: check object_size in kasan_complete_mode_report_info 2023-12-10 16:51:47 -08:00
report.c kasan: use unchecked __memset internally 2023-10-18 14:34:15 -07:00
shadow.c kasan: use unchecked __memset internally 2023-10-18 14:34:15 -07:00
sw_tags.c kasan: use internal prototypes matching gcc-13 builtins 2023-06-09 16:25:19 -07:00
tags.c kasan: use stack_depot_put for tag-based modes 2023-12-10 16:51:47 -08:00