diff options
authorAndrey Konovalov <andreyknvl@google.com>2021-03-12 21:08:10 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-03-13 11:27:31 -0800
commitf9d79e8dce4077d3c6ab739c808169dfa99af9ef (patch)
parent96cfe2c0fd23ea7c2368d14f769d287e7ae1082e (diff)
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>
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d4580e4215d8..3cd1c0ce4d06 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1282,6 +1282,12 @@ static __always_inline bool free_pages_prepare(struct page *page,
kernel_poison_pages(page, 1 << order);
+ * 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.
@@ -1290,8 +1296,6 @@ static __always_inline bool free_pages_prepare(struct page *page,
debug_pagealloc_unmap_pages(page, 1 << order);
- kasan_free_nondeferred_pages(page, order);
return true;

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