This is a note to let you know that I've just added the patch titled kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kasan-mm-fix-crash-with-hw_tags-and-debug_pagealloc.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From f9d79e8dce4077d3c6ab739c808169dfa99af9ef Mon Sep 17 00:00:00 2001 From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Date: Fri, 12 Mar 2021 21:08:10 -0800 Subject: kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC From: Andrey Konovalov <andreyknvl@xxxxxxxxxx> 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.andreyknvl@xxxxxxxxxx Fixes: 94ab5b61ee16 ("kasan, arm64: enable CONFIG_KASAN_HW_TAGS") Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Peter Collingbourne <pcc@xxxxxxxxxx> Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx> Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx> Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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; } Patches currently in stable-queue which might be from andreyknvl@xxxxxxxxxx are queue-5.11/kasan-mm-fix-crash-with-hw_tags-and-debug_pagealloc.patch queue-5.11/kasan-fix-memory-corruption-in-kasan_bitops_tags-tes.patch queue-5.11/kasan-fix-kasan_stack-dependency-for-hw_tags.patch queue-5.11/arm64-kasan-fix-page_alloc-tagging-with-debug_virtual.patch