From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, andreyknvl@google.com,
aryabinin@virtuozzo.com, Branislav.Rankov@arm.com,
catalin.marinas@arm.com, dvyukov@google.com, elver@google.com,
eugenis@google.com, glider@google.com, gor@linux.ibm.com,
kevin.brodsky@arm.com, linux-mm@kvack.org,
mm-commits@vger.kernel.org, torvalds@linux-foundation.org,
vincenzo.frascino@arm.com, will.deacon@arm.com
Subject: [patch 25/60] arm64: mte: reset the page tag in page->flags
Date: Tue, 22 Dec 2020 12:01:31 -0800 [thread overview]
Message-ID: <20201222200131.HtyUt5vvG%akpm@linux-foundation.org> (raw)
In-Reply-To: <20201222115844.d30aaef7df6f5b120d3e0c3d@linux-foundation.org>
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
Subject: arm64: mte: reset the page tag in page->flags
The hardware tag-based KASAN for compatibility with the other modes stores
the tag associated to a page in page->flags. Due to this the kernel
faults on access when it allocates a page with an initial tag and the user
changes the tags.
Reset the tag associated by the kernel to a page in all the meaningful
places to prevent kernel faults on access.
Note: An alternative to this approach could be to modify page_to_virt().
This though could end up being racy, in fact if a CPU checks the
PG_mte_tagged bit and decides that the page is not tagged but another CPU
maps the same with PROT_MTE and becomes tagged the subsequent kernel
access would fail.
Link: https://lkml.kernel.org/r/9073d4e973747a6f78d5bdd7ebe17f290d087096.1606161801.git.andreyknvl@google.com
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@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>
---
arch/arm64/kernel/hibernate.c | 5 +++++
arch/arm64/kernel/mte.c | 9 +++++++++
arch/arm64/mm/copypage.c | 9 +++++++++
arch/arm64/mm/mteswap.c | 9 +++++++++
4 files changed, 32 insertions(+)
--- a/arch/arm64/kernel/hibernate.c~arm64-mte-reset-the-page-tag-in-page-flags
+++ a/arch/arm64/kernel/hibernate.c
@@ -371,6 +371,11 @@ static void swsusp_mte_restore_tags(void
unsigned long pfn = xa_state.xa_index;
struct page *page = pfn_to_online_page(pfn);
+ /*
+ * It is not required to invoke page_kasan_tag_reset(page)
+ * at this point since the tags stored in page->flags are
+ * already restored.
+ */
mte_restore_page_tags(page_address(page), tags);
mte_free_tag_storage(tags);
--- a/arch/arm64/kernel/mte.c~arm64-mte-reset-the-page-tag-in-page-flags
+++ a/arch/arm64/kernel/mte.c
@@ -34,6 +34,15 @@ static void mte_sync_page_tags(struct pa
return;
}
+ page_kasan_tag_reset(page);
+ /*
+ * We need smp_wmb() in between setting the flags and clearing the
+ * tags because if another thread reads page->flags and builds a
+ * tagged address out of it, there is an actual dependency to the
+ * memory access, but on the current thread we do not guarantee that
+ * the new page->flags are visible before the tags were updated.
+ */
+ smp_wmb();
mte_clear_page_tags(page_address(page));
}
--- a/arch/arm64/mm/copypage.c~arm64-mte-reset-the-page-tag-in-page-flags
+++ a/arch/arm64/mm/copypage.c
@@ -23,6 +23,15 @@ void copy_highpage(struct page *to, stru
if (system_supports_mte() && test_bit(PG_mte_tagged, &from->flags)) {
set_bit(PG_mte_tagged, &to->flags);
+ page_kasan_tag_reset(to);
+ /*
+ * We need smp_wmb() in between setting the flags and clearing the
+ * tags because if another thread reads page->flags and builds a
+ * tagged address out of it, there is an actual dependency to the
+ * memory access, but on the current thread we do not guarantee that
+ * the new page->flags are visible before the tags were updated.
+ */
+ smp_wmb();
mte_copy_page_tags(kto, kfrom);
}
}
--- a/arch/arm64/mm/mteswap.c~arm64-mte-reset-the-page-tag-in-page-flags
+++ a/arch/arm64/mm/mteswap.c
@@ -53,6 +53,15 @@ bool mte_restore_tags(swp_entry_t entry,
if (!tags)
return false;
+ page_kasan_tag_reset(page);
+ /*
+ * We need smp_wmb() in between setting the flags and clearing the
+ * tags because if another thread reads page->flags and builds a
+ * tagged address out of it, there is an actual dependency to the
+ * memory access, but on the current thread we do not guarantee that
+ * the new page->flags are visible before the tags were updated.
+ */
+ smp_wmb();
mte_restore_page_tags(page_address(page), tags);
return true;
_
next prev parent reply other threads:[~2020-12-22 20:01 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-22 19:58 incoming Andrew Morton
2020-12-22 20:00 ` [patch 01/60] kasan: drop unnecessary GPL text from comment headers Andrew Morton
2020-12-22 20:00 ` [patch 02/60] kasan: KASAN_VMALLOC depends on KASAN_GENERIC Andrew Morton
2020-12-22 20:00 ` [patch 03/60] kasan: group vmalloc code Andrew Morton
2020-12-22 20:00 ` [patch 04/60] kasan: shadow declarations only for software modes Andrew Morton
2020-12-22 20:00 ` [patch 05/60] kasan: rename (un)poison_shadow to (un)poison_range Andrew Morton
2020-12-22 20:00 ` [patch 06/60] kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_* Andrew Morton
2020-12-22 20:00 ` [patch 07/60] kasan: only build init.c for software modes Andrew Morton
2020-12-22 20:00 ` [patch 08/60] kasan: split out shadow.c from common.c Andrew Morton
2020-12-22 20:00 ` [patch 09/60] kasan: define KASAN_MEMORY_PER_SHADOW_PAGE Andrew Morton
2020-12-22 20:00 ` [patch 10/60] kasan: rename report and tags files Andrew Morton
2020-12-22 20:00 ` [patch 11/60] kasan: don't duplicate config dependencies Andrew Morton
2020-12-22 20:00 ` [patch 12/60] kasan: hide invalid free check implementation Andrew Morton
2020-12-22 20:00 ` [patch 13/60] kasan: decode stack frame only with KASAN_STACK_ENABLE Andrew Morton
2020-12-22 20:00 ` [patch 14/60] kasan, arm64: only init shadow for software modes Andrew Morton
2020-12-22 20:00 ` [patch 15/60] kasan, arm64: only use kasan_depth " Andrew Morton
2020-12-22 20:01 ` [patch 16/60] kasan, arm64: move initialization message Andrew Morton
2020-12-22 20:01 ` [patch 17/60] kasan, arm64: rename kasan_init_tags and mark as __init Andrew Morton
2020-12-22 20:01 ` [patch 18/60] kasan: rename addr_has_shadow to addr_has_metadata Andrew Morton
2020-12-22 20:01 ` [patch 19/60] kasan: rename print_shadow_for_address to print_memory_metadata Andrew Morton
2020-12-22 20:01 ` [patch 20/60] kasan: rename SHADOW layout macros to META Andrew Morton
2020-12-22 20:01 ` [patch 21/60] kasan: separate metadata_fetch_row for each mode Andrew Morton
2020-12-22 20:01 ` [patch 22/60] kasan: introduce CONFIG_KASAN_HW_TAGS Andrew Morton
2020-12-22 20:01 ` [patch 23/60] arm64: enable armv8.5-a asm-arch option Andrew Morton
2020-12-22 20:01 ` [patch 24/60] arm64: mte: add in-kernel MTE helpers Andrew Morton
2020-12-22 20:01 ` Andrew Morton [this message]
2020-12-22 20:01 ` [patch 26/60] arm64: mte: add in-kernel tag fault handler Andrew Morton
2020-12-22 20:01 ` [patch 27/60] arm64: kasan: allow enabling in-kernel MTE Andrew Morton
2020-12-22 20:01 ` [patch 28/60] arm64: mte: convert gcr_user into an exclude mask Andrew Morton
2020-12-22 20:01 ` [patch 29/60] arm64: mte: switch GCR_EL1 in kernel entry and exit Andrew Morton
2020-12-22 20:01 ` [patch 30/60] kasan, mm: untag page address in free_reserved_area Andrew Morton
2020-12-22 20:01 ` [patch 31/60] arm64: kasan: align allocations for HW_TAGS Andrew Morton
2020-12-22 20:01 ` [patch 32/60] arm64: kasan: add arch layer for memory tagging helpers Andrew Morton
2020-12-22 20:01 ` [patch 33/60] kasan: define KASAN_GRANULE_SIZE for HW_TAGS Andrew Morton
2020-12-22 20:02 ` [patch 34/60] kasan, x86, s390: update undef CONFIG_KASAN Andrew Morton
2020-12-22 20:02 ` [patch 35/60] kasan, arm64: expand CONFIG_KASAN checks Andrew Morton
2020-12-22 20:02 ` [patch 36/60] kasan, arm64: implement HW_TAGS runtime Andrew Morton
2020-12-22 20:02 ` [patch 37/60] kasan, arm64: print report from tag fault handler Andrew Morton
2020-12-22 20:02 ` [patch 38/60] kasan, mm: reset tags when accessing metadata Andrew Morton
2020-12-22 20:02 ` [patch 39/60] kasan, arm64: enable CONFIG_KASAN_HW_TAGS Andrew Morton
2020-12-22 20:02 ` [patch 40/60] kasan: add documentation for hardware tag-based mode Andrew Morton
2020-12-22 20:02 ` [patch 41/60] kselftest/arm64: check GCR_EL1 after context switch Andrew Morton
2020-12-22 20:02 ` [patch 42/60] kasan: simplify quarantine_put call site Andrew Morton
2020-12-22 20:02 ` [patch 43/60] kasan: rename get_alloc/free_info Andrew Morton
2020-12-22 20:02 ` [patch 44/60] kasan: introduce set_alloc_info Andrew Morton
2020-12-22 20:02 ` [patch 45/60] kasan, arm64: unpoison stack only with CONFIG_KASAN_STACK Andrew Morton
2020-12-22 20:02 ` [patch 46/60] kasan: allow VMAP_STACK for HW_TAGS mode Andrew Morton
2020-12-22 20:02 ` [patch 47/60] kasan: remove __kasan_unpoison_stack Andrew Morton
2020-12-22 20:02 ` [patch 48/60] kasan: inline kasan_reset_tag for tag-based modes Andrew Morton
2020-12-22 20:02 ` [patch 49/60] kasan: inline random_tag for HW_TAGS Andrew Morton
2020-12-22 20:02 ` [patch 50/60] kasan: open-code kasan_unpoison_slab Andrew Morton
2020-12-22 20:03 ` [patch 51/60] kasan: inline (un)poison_range and check_invalid_free Andrew Morton
2020-12-22 20:03 ` [patch 52/60] kasan: add and integrate kasan boot parameters Andrew Morton
2020-12-22 20:03 ` [patch 53/60] kasan, mm: check kasan_enabled in annotations Andrew Morton
2020-12-22 20:03 ` [patch 54/60] kasan, mm: rename kasan_poison_kfree Andrew Morton
2020-12-22 20:03 ` [patch 55/60] kasan: don't round_up too much Andrew Morton
2020-12-22 20:03 ` [patch 56/60] kasan: simplify assign_tag and set_tag calls Andrew Morton
2020-12-22 20:03 ` [patch 57/60] kasan: clarify comment in __kasan_kfree_large Andrew Morton
2020-12-22 20:03 ` [patch 58/60] kasan: sanitize objects when metadata doesn't fit Andrew Morton
2020-12-22 20:03 ` [patch 59/60] kasan, mm: allow cache merging with no metadata Andrew Morton
2020-12-22 20:03 ` [patch 60/60] kasan: update documentation Andrew Morton
2020-12-22 21:43 ` incoming Linus Torvalds
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