From: Greg Kroah-Hartman <gre...@linuxfoundation.org> From: Andrey Konovalov <andreyk...@google.com>
commit f9d79e8dce4077d3c6ab739c808169dfa99af9ef upstream. 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.andreyk...@google.com Fixes: 94ab5b61ee16 ("kasan, arm64: enable CONFIG_KASAN_HW_TAGS") Signed-off-by: Andrey Konovalov <andreyk...@google.com> Cc: Catalin Marinas <catalin.mari...@arm.com> Cc: Will Deacon <will.dea...@arm.com> Cc: Vincenzo Frascino <vincenzo.frasc...@arm.com> Cc: Dmitry Vyukov <dvyu...@google.com> Cc: Andrey Ryabinin <aryabi...@virtuozzo.com> Cc: Alexander Potapenko <gli...@google.com> Cc: Marco Elver <el...@google.com> Cc: Peter Collingbourne <p...@google.com> Cc: Evgenii Stepanov <euge...@google.com> Cc: Branislav Rankov <branislav.ran...@arm.com> Cc: Kevin Brodsky <kevin.brod...@arm.com> Cc: Christoph Hellwig <h...@infradead.org> Cc: <sta...@vger.kernel.org> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- mm/page_alloc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1282,6 +1282,12 @@ static __always_inline bool free_pages_p 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_p debug_pagealloc_unmap_pages(page, 1 << order); - kasan_free_nondeferred_pages(page, order); - return true; }
