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Benjamin Gray 2597c9947b kasan: guard release_free_meta() shadow access with kasan_arch_is_ready()

release_free_meta() accesses the shadow directly through the path

  kasan_slab_free
    __kasan_slab_free
      kasan_release_object_meta
        release_free_meta
          kasan_mem_to_shadow

There are no kasan_arch_is_ready() guards here, allowing an oops when the
shadow is not initialized.  The oops can be seen on a Power8 KVM guest.

This patch adds the guard to release_free_meta(), as it's the first level
that specifically requires the shadow.

It is safe to put the guard at the start of this function, before the
stack put: only kasan_save_free_info() can initialize the saved stack,
which itself is guarded with kasan_arch_is_ready() by its caller
poison_slab_object().  If the arch becomes ready before
release_free_meta() then we will not observe KASAN_SLAB_FREE_META in the
object's shadow, so we will not put an uninitialized stack either.

Link: https://lkml.kernel.org/r/20240213033958.139383-1-bgray@linux.ibm.com
Fixes: 63b85ac56a64 ("kasan: stop leaking stack trace handles")
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2024-02-20 14:20:50 -08:00

common.c

Many singleton patches against the MM code. The patch series which

2024-01-09 11:18:47 -08:00

generic.c

kasan: guard release_free_meta() shadow access with kasan_arch_is_ready()

2024-02-20 14:20:50 -08:00

hw_tags.c

kasan: check kasan_vmalloc_enabled in vmalloc tests

2023-12-29 11:58:45 -08:00

init.c

kasan: Add (pmd|pud)_init for LoongArch zero_(pud|p4d)_populate process