FROMGIT: kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC
Currently, kasan_free_nondeferred_pages()->kasan_free_pages() is called
after debug_pagealloc_unmap_pages(). This causes a crash when
debug_pagealloc is enabled, as HW_TAGS KASAN can't set tags on an
unmapped page.
This patch puts kasan_free_nondeferred_pages() before
debug_pagealloc_unmap_pages() and arch_free_page(), which can also make
the page unavailable.
Link: https://lkml.kernel.org/r/24cd7db274090f0e5bc3adcdc7399243668e3171.1614987311.git.andreyknvl@google.com
Fixes: 94ab5b61ee16 ("kasan, arm64: enable CONFIG_KASAN_HW_TAGS")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit f9d79e8dce4077d3c6ab739c808169dfa99af9ef
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm)
Bug: 182930667
Signed-off-by: Alexander Potapenko <glider@google.com>
Change-Id: Iab88e1e7ab63e6e5ec4b5e0160baf16e0335ee9e
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6fc7273..bdb6a55 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1285,6 +1285,12 @@ static __always_inline bool free_pages_prepare(struct page *page,
kernel_poison_pages(page, 1 << order, 0);
/*
+ * With hardware tag-based KASAN, memory tags must be set before the
+ * page becomes unavailable via debug_pagealloc or arch_free_page.
+ */
+ kasan_free_nondeferred_pages(page, order);
+
+ /*
* arch_free_page() can make the page's contents inaccessible. s390
* does this. So nothing which can access the page's contents should
* happen after this.
@@ -1294,8 +1300,6 @@ static __always_inline bool free_pages_prepare(struct page *page,
if (debug_pagealloc_enabled_static())
kernel_map_pages(page, 1 << order, 0);
- kasan_free_nondeferred_pages(page, order);
-
return true;
}