[PATCH 0/5] mm/slub: Improve data handling of krealloc() when orig_size is enabled

[Feng Tang]

Danilo Krummrich's patch [1] raised one problem about krealloc() that
its caller doesn't know what's the actual request size, say the object
is 64 bytes kmalloc one, but the original caller may only requested 48
bytes. And when krealloc() shrinks or grows in the same object, or
allocate a new bigger object, it lacks this 'original size' information
to do accurate data preserving or zeroing (when __GFP_ZERO is set).

And when some slub debug option is enabled, kmalloc caches do have this
'orig_size' feature. As suggested by Vlastimil, utilize it to do more
accurate data handling, as well as enforce the kmalloc-redzone sanity check.

To make the 'orig_size' accurate, we adjust some kasan/slub meta data
handling. Also add a slub kunit test case for krealloc().

This patchset has dependency over patches in both -mm tree and -slab
trees, so it is written based on linux-next tree '20240905' version.

[1]. https://lore.kernel.org/lkml/20240812223707.32049-1-dakr@xxxxxxxxxx/

Thanks,
Feng

Feng Tang (5):
  mm/kasan: Don't store metadata inside kmalloc object when
    slub_debug_orig_size is on
  mm/slub: Consider kfence case for get_orig_size()
  mm/slub: Improve redzone check and zeroing for krealloc()
  kunit: kfence: Make KFENCE_TEST_REQUIRES macro available for all kunit
    case
  mm/slub, kunit: Add testcase for krealloc redzone and zeroing

 include/kunit/test.h    |   6 ++
 lib/slub_kunit.c        |  46 +++++++++++++++
 mm/kasan/generic.c      |   5 +-
 mm/kfence/kfence_test.c |   9 +--
 mm/slab.h               |   6 ++
 mm/slab_common.c        |  84 ---------------------------
 mm/slub.c               | 125 ++++++++++++++++++++++++++++++++++------
 7 files changed, 171 insertions(+), 110 deletions(-)

-- 
2.34.1