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KASAN marks caches that are sanitized with the SLAB_KASAN cache flag. Currently if the metadata that is appended after the object (stores e.g. stack trace ids) doesn't fit into KMALLOC_MAX_SIZE (can only happen with SLAB, see the comment in the patch), KASAN turns off sanitization completely. With this change sanitization of the object data is always enabled. However the metadata is only stored when it fits. Instead of checking for SLAB_KASAN flag accross the code to find out whether the metadata is there, use cache->kasan_info.alloc/free_meta_offset. As 0 can be a valid value for free_meta_offset, introduce KASAN_NO_FREE_META as an indicator that the free metadata is missing. Along the way rework __kasan_cache_create() and add claryfying comments. Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Link: https://linux-review.googlesource.com/id/Icd947e2bea054cb5cfbdc6cf6652227d97032dcb
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