kasan: fix zeroing vmalloc memory with HW_TAGS

HW_TAGS KASAN skips zeroing page_alloc allocations backing vmalloc
mappings via __GFP_SKIP_ZERO.  Instead, these pages are zeroed via
kasan_unpoison_vmalloc() by passing the KASAN_VMALLOC_INIT flag.

The problem is that __kasan_unpoison_vmalloc() does not zero pages when
either kasan_vmalloc_enabled() or is_vmalloc_or_module_addr() fail.

Thus:

1. Change __vmalloc_node_range() to only set KASAN_VMALLOC_INIT when
   __GFP_SKIP_ZERO is set.

2. Change __kasan_unpoison_vmalloc() to always zero pages when the
   KASAN_VMALLOC_INIT flag is set.

3. Add WARN_ON() asserts to check that KASAN_VMALLOC_INIT cannot be set
   in other early return paths of __kasan_unpoison_vmalloc().

Also clean up the comment in __kasan_unpoison_vmalloc.

Link: https://lkml.kernel.org/r/4bc503537efdc539ffc3f461c1b70162eea31cf6.1654798516.git.andreyknvl@google.com
Fixes: 23689e91fb22 ("kasan, vmalloc: add vmalloc tagging for HW_TAGS")
Signed-off-by: Andrey Konovalov <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions