Commit e9d0ca92 authored Mar 24, 2022 by Andrey Konovalov Committed by Linus Torvalds Mar 24, 2022

kasan, page_alloc: rework kasan_unpoison_pages call site

Rework the checks around kasan_unpoison_pages() call in post_alloc_hook().

The logical condition for calling this function is:

 - If a software KASAN mode is enabled, we need to mark shadow memory.

 - Otherwise, HW_TAGS KASAN is enabled, and it only makes sense to set
   tags if they haven't already been cleared by tag_clear_highpage(),
   which is indicated by init_tags.

This patch concludes the changes for post_alloc_hook().

Link: https://lkml.kernel.org/r/0ecebd0d7ccd79150e3620ea4185a32d3dfe912f.1643047180.git.andreyknvl@google.com


Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7e3cbba6

mm/page_alloc.c

+12 −7

Original line number	Diff line number	Diff line
		@@ -2382,16 +2382,21 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
		/* Note that memory is already initialized by the loop above. */
		init = false;
		}
		if (kasan_has_integrated_init()) {
		if (!init_tags) {
		/*
		* If either a software KASAN mode is enabled, or,
		* in the case of hardware tag-based KASAN,
		* if memory tags have not been cleared via tag_clear_highpage().
		*/
		if (IS_ENABLED(CONFIG_KASAN_GENERIC) \|\|
		IS_ENABLED(CONFIG_KASAN_SW_TAGS) \|\|
		kasan_hw_tags_enabled() && !init_tags) {
		/* Mark shadow memory or set memory tags. */
		kasan_unpoison_pages(page, order, init);

		/* Note that memory is already initialized by KASAN. */
		if (kasan_has_integrated_init())
		init = false;
		}
		} else {
		kasan_unpoison_pages(page, order, init);
		}
		/* If memory is still not initialized, do it now. */
		if (init)
		kernel_init_free_pages(page, 1 << order);