[patch 072/118] kasan: optimize large kmalloc poisoning
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2021-02-26 01:20:07
Also in:
mm-commits
From: Andrey Konovalov <redacted> Subject: kasan: optimize large kmalloc poisoning Similarly to kasan_kmalloc(), kasan_kmalloc_large() doesn't need to unpoison the object as it as already unpoisoned by alloc_pages() (or by ksize() for krealloc()). This patch changes kasan_kmalloc_large() to only poison the redzone. Link: https://lkml.kernel.org/r/33dee5aac0e550ad7f8e26f590c9b02c6129b4a3.1612546384.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <redacted> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <redacted> Cc: Branislav Rankov <redacted> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <redacted> Cc: Kevin Brodsky <redacted> Cc: Peter Collingbourne <redacted> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <redacted> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- mm/kasan/common.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)
--- a/mm/kasan/common.c~kasan-optimize-large-kmalloc-poisoning
+++ a/mm/kasan/common.c@@ -494,7 +494,6 @@ EXPORT_SYMBOL(__kasan_kmalloc); void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags) { - struct page *page; unsigned long redzone_start; unsigned long redzone_end;
@@ -504,12 +503,23 @@ void * __must_check __kasan_kmalloc_larg if (unlikely(ptr == NULL)) return NULL; - page = virt_to_page(ptr); + /* + * The object has already been unpoisoned by kasan_alloc_pages() for + * alloc_pages() or by ksize() for krealloc(). + */ + + /* + * The redzone has byte-level precision for the generic mode. + * Partially poison the last object granule to cover the unaligned + * part of the redzone. + */ + if (IS_ENABLED(CONFIG_KASAN_GENERIC)) + kasan_poison_last_granule(ptr, size); + + /* Poison the aligned part of the redzone. */ redzone_start = round_up((unsigned long)(ptr + size), KASAN_GRANULE_SIZE); - redzone_end = (unsigned long)ptr + page_size(page); - - kasan_unpoison(ptr, size); + redzone_end = (unsigned long)ptr + page_size(virt_to_page(ptr)); kasan_poison((void *)redzone_start, redzone_end - redzone_start, KASAN_PAGE_REDZONE);
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