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 38/78] arm64: mte: reset the page tag in page->flags
Date: Fri, 18 Dec 2020 14:03:29 -0800 [thread overview]
Message-ID: <20201218220329.YlRLmNiSU%akpm@linux-foundation.org> (raw)
In-Reply-To: <20201218140046.497484741326828e5b5d46ec@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:[~2020-12-18 22:03 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-18 22:00 incoming Andrew Morton
2020-12-18 22:01 ` [patch 01/78] mm/memcg: bail early from swap accounting if memcg disabled Andrew Morton
2020-12-18 22:01 ` [patch 02/78] mm/memcg: warning on !memcg after readahead page charged Andrew Morton
2020-12-18 22:01 ` [patch 03/78] mm/memcg: remove unused definitions Andrew Morton
2020-12-18 22:01 ` [patch 04/78] mm, kvm: account kvm_vcpu_mmap to kmemcg Andrew Morton
2020-12-18 22:01 ` [patch 05/78] mm/memcontrol:rewrite mem_cgroup_page_lruvec() Andrew Morton
2020-12-18 22:01 ` [patch 06/78] epoll: check for events when removing a timed out thread from the wait queue Andrew Morton
2020-12-18 22:01 ` [patch 07/78] epoll: simplify signal handling Andrew Morton
2020-12-18 22:01 ` [patch 08/78] epoll: pull fatal signal checks into ep_send_events() Andrew Morton
2020-12-18 22:01 ` [patch 09/78] epoll: move eavail next to the list_empty_careful check Andrew Morton
2020-12-18 22:01 ` [patch 10/78] epoll: simplify and optimize busy loop logic Andrew Morton
2020-12-18 22:02 ` [patch 11/78] epoll: pull all code between fetch_events and send_event into the loop Andrew Morton
2020-12-18 22:02 ` [patch 12/78] epoll: replace gotos with a proper loop Andrew Morton
2020-12-18 22:02 ` [patch 13/78] epoll: eliminate unnecessary lock for zero timeout Andrew Morton
2020-12-18 22:02 ` [patch 14/78] kasan: drop unnecessary GPL text from comment headers Andrew Morton
2020-12-18 22:02 ` [patch 15/78] kasan: KASAN_VMALLOC depends on KASAN_GENERIC Andrew Morton
2020-12-18 22:02 ` [patch 16/78] kasan: group vmalloc code Andrew Morton
2020-12-18 22:02 ` [patch 17/78] kasan: shadow declarations only for software modes Andrew Morton
2020-12-18 22:02 ` [patch 18/78] kasan: rename (un)poison_shadow to (un)poison_range Andrew Morton
2020-12-18 22:02 ` [patch 19/78] kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_* Andrew Morton
2020-12-18 22:02 ` [patch 20/78] kasan: only build init.c for software modes Andrew Morton
2020-12-18 22:02 ` [patch 21/78] kasan: split out shadow.c from common.c Andrew Morton
2020-12-19 0:28 ` Marco Elver
2020-12-19 1:13 ` Andrew Morton
2020-12-19 10:01 ` Marco Elver
2020-12-19 10:11 ` Marco Elver
2020-12-19 18:01 ` Andrey Konovalov
2020-12-19 19:17 ` Linus Torvalds
2020-12-19 19:26 ` Linus Torvalds
2020-12-21 9:46 ` Alexander Potapenko
2020-12-21 17:41 ` Linus Torvalds
2020-12-22 18:38 ` Andrew Morton
2020-12-22 12:00 ` kernel test robot
2020-12-18 22:02 ` [patch 22/78] kasan: define KASAN_MEMORY_PER_SHADOW_PAGE Andrew Morton
2020-12-18 22:02 ` [patch 23/78] kasan: rename report and tags files Andrew Morton
2020-12-18 22:02 ` [patch 24/78] kasan: don't duplicate config dependencies Andrew Morton
2020-12-18 22:02 ` [patch 25/78] kasan: hide invalid free check implementation Andrew Morton
2020-12-18 22:02 ` [patch 26/78] kasan: decode stack frame only with KASAN_STACK_ENABLE Andrew Morton
2020-12-18 22:02 ` [patch 27/78] kasan, arm64: only init shadow for software modes Andrew Morton
2020-12-18 22:02 ` [patch 28/78] kasan, arm64: only use kasan_depth " Andrew Morton
2020-12-18 22:03 ` [patch 29/78] kasan, arm64: move initialization message Andrew Morton
2020-12-18 22:03 ` [patch 30/78] kasan, arm64: rename kasan_init_tags and mark as __init Andrew Morton
2020-12-18 22:03 ` [patch 31/78] kasan: rename addr_has_shadow to addr_has_metadata Andrew Morton
2020-12-18 22:03 ` [patch 32/78] kasan: rename print_shadow_for_address to print_memory_metadata Andrew Morton
2020-12-18 22:03 ` [patch 33/78] kasan: rename SHADOW layout macros to META Andrew Morton
2020-12-18 22:03 ` [patch 34/78] kasan: separate metadata_fetch_row for each mode Andrew Morton
2020-12-18 22:03 ` [patch 35/78] kasan: introduce CONFIG_KASAN_HW_TAGS Andrew Morton
2020-12-18 22:03 ` [patch 36/78] arm64: enable armv8.5-a asm-arch option Andrew Morton
2020-12-18 22:03 ` [patch 37/78] arm64: mte: add in-kernel MTE helpers Andrew Morton
2020-12-18 22:03 ` Andrew Morton [this message]
2020-12-18 22:03 ` [patch 39/78] arm64: mte: add in-kernel tag fault handler Andrew Morton
2020-12-18 22:03 ` [patch 40/78] arm64: kasan: allow enabling in-kernel MTE Andrew Morton
2020-12-18 22:03 ` [patch 41/78] arm64: mte: convert gcr_user into an exclude mask Andrew Morton
2020-12-18 22:03 ` [patch 42/78] arm64: mte: switch GCR_EL1 in kernel entry and exit Andrew Morton
2020-12-18 22:03 ` [patch 43/78] kasan, mm: untag page address in free_reserved_area Andrew Morton
2020-12-18 22:03 ` [patch 44/78] arm64: kasan: align allocations for HW_TAGS Andrew Morton
2020-12-18 22:03 ` [patch 45/78] arm64: kasan: add arch layer for memory tagging helpers Andrew Morton
2020-12-18 22:03 ` [patch 46/78] kasan: define KASAN_GRANULE_SIZE for HW_TAGS Andrew Morton
2020-12-18 22:03 ` [patch 47/78] kasan, x86, s390: update undef CONFIG_KASAN Andrew Morton
2020-12-18 22:04 ` [patch 48/78] kasan, arm64: expand CONFIG_KASAN checks Andrew Morton
2020-12-18 22:04 ` [patch 49/78] kasan, arm64: implement HW_TAGS runtime Andrew Morton
2020-12-18 22:04 ` [patch 50/78] kasan, arm64: print report from tag fault handler Andrew Morton
2020-12-18 22:04 ` [patch 51/78] kasan, mm: reset tags when accessing metadata Andrew Morton
2020-12-18 22:04 ` [patch 52/78] kasan, arm64: enable CONFIG_KASAN_HW_TAGS Andrew Morton
2020-12-18 22:04 ` [patch 53/78] kasan: add documentation for hardware tag-based mode Andrew Morton
2020-12-18 22:04 ` [patch 54/78] kselftest/arm64: check GCR_EL1 after context switch Andrew Morton
2020-12-18 22:04 ` [patch 55/78] kasan: simplify quarantine_put call site Andrew Morton
2020-12-18 22:04 ` [patch 56/78] kasan: rename get_alloc/free_info Andrew Morton
2020-12-18 22:04 ` [patch 57/78] kasan: introduce set_alloc_info Andrew Morton
2020-12-18 22:04 ` [patch 58/78] kasan, arm64: unpoison stack only with CONFIG_KASAN_STACK Andrew Morton
2020-12-18 22:04 ` [patch 59/78] kasan: allow VMAP_STACK for HW_TAGS mode Andrew Morton
2020-12-18 22:04 ` [patch 60/78] kasan: remove __kasan_unpoison_stack Andrew Morton
2020-12-18 22:04 ` [patch 61/78] kasan: inline kasan_reset_tag for tag-based modes Andrew Morton
2020-12-18 22:04 ` [patch 62/78] kasan: inline random_tag for HW_TAGS Andrew Morton
2020-12-18 22:04 ` [patch 63/78] kasan: open-code kasan_unpoison_slab Andrew Morton
2020-12-18 22:04 ` [patch 64/78] kasan: inline (un)poison_range and check_invalid_free Andrew Morton
2020-12-22 14:02 ` kernel test robot
2020-12-18 22:05 ` [patch 65/78] kasan: add and integrate kasan boot parameters Andrew Morton
2020-12-18 22:05 ` [patch 66/78] kasan, mm: check kasan_enabled in annotations Andrew Morton
2020-12-18 22:05 ` [patch 67/78] kasan, mm: rename kasan_poison_kfree Andrew Morton
2020-12-18 22:05 ` [patch 68/78] kasan: don't round_up too much Andrew Morton
2020-12-18 22:05 ` [patch 69/78] kasan: simplify assign_tag and set_tag calls Andrew Morton
2020-12-18 22:05 ` [patch 70/78] kasan: clarify comment in __kasan_kfree_large Andrew Morton
2020-12-18 22:05 ` [patch 71/78] kasan: sanitize objects when metadata doesn't fit Andrew Morton
2020-12-18 22:05 ` [patch 72/78] kasan, mm: allow cache merging with no metadata Andrew Morton
2020-12-18 22:05 ` [patch 73/78] kasan: update documentation Andrew Morton
2020-12-18 22:05 ` [patch 74/78] mm/Kconfig: fix spelling mistake "whats" -> "what's" Andrew Morton
2020-12-18 22:05 ` [patch 75/78] epoll: convert internal api to timespec64 Andrew Morton
2020-12-18 22:05 ` [patch 76/78] epoll: add syscall epoll_pwait2 Andrew Morton
2020-12-18 22:05 ` [patch 77/78] epoll: wire up " Andrew Morton
2020-12-18 22:05 ` [patch 78/78] selftests/filesystems: expand epoll with epoll_pwait2 Andrew Morton
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