+ kasan-mm-untag-page-address-in-free_reserved_area.patch added to -mm tree

* + kasan-mm-untag-page-address-in-free_reserved_area.patch added to -mm tree
@ 2020-11-10 22:57 akpm
  0 siblings, 0 replies; 2+ messages in thread
From: akpm @ 2020-11-10 22:57 UTC (permalink / raw)
  To: akpm, andreyknvl, aryabinin, Branislav.Rankov, catalin.marinas,
	dvyukov, elver, eugenis, glider, gor, kevin.brodsky, mm-commits,
	vincenzo.frascino, will.deacon


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@arm.com>
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/c9b863d85d5a22af9b7a294b99ea98e1fe47d7a9.1605046192.git.andreyknvl@google.com
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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
@@ -7603,6 +7603,11 @@ 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@arm.com 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


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