The patch titled
Subject: kasan, mm: untag page address in free_reserved_area
has been added to the -mm tree. Its filename is
kasan-mm-untag-page-address-in-free_reserved_area.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-mm-untag-page-address-in-free_reserved_area.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-mm-untag-page-address-in-free_reserved_area.patch
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------------------------------------------------------
From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Subject: kasan, mm: untag page address in free_reserved_area
free_reserved_area() memsets the pages belonging to a given memory area.
As that memory hasn't been allocated via page_alloc, the KASAN tags that
those pages have are 0x00. As the result the memset might result in a tag
mismatch.
Untag the address to avoid spurious faults.
Link: https://lkml.kernel.org/r/ebef6425f4468d063e2f09c1b62ccbb2236b71d3.1606161801.git.andreyknvl@xxxxxxxxxx
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
Tested-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/mm/page_alloc.c~kasan-mm-untag-page-address-in-free_reserved_area
+++ a/mm/page_alloc.c
@@ -7662,6 +7662,11 @@ unsigned long free_reserved_area(void *s
* alias for the memset().
*/
direct_map_addr = page_address(page);
+ /*
+ * Perform a kasan-unchecked memset() since this memory
+ * has not been initialized.
+ */
+ direct_map_addr = kasan_reset_tag(direct_map_addr);
if ((unsigned int)poison <= 0xFF)
memset(direct_map_addr, poison, PAGE_SIZE);
_
Patches currently in -mm which might be from vincenzo.frascino@xxxxxxx are
mm-vmalloc-fix-kasan-shadow-poisoning-size.patch
arm64-enable-armv85-a-asm-arch-option.patch
arm64-mte-add-in-kernel-mte-helpers.patch
arm64-mte-reset-the-page-tag-in-page-flags.patch
arm64-mte-add-in-kernel-tag-fault-handler.patch
arm64-kasan-allow-enabling-in-kernel-mte.patch
arm64-mte-convert-gcr_user-into-an-exclude-mask.patch
arm64-mte-switch-gcr_el1-in-kernel-entry-and-exit.patch
kasan-mm-untag-page-address-in-free_reserved_area.patch
kselftest-arm64-check-gcr_el1-after-context-switch.patch
