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UPSTREAM: kasan, mm, arm64: tag non slab memory allocated via pagealloc

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(Upstream commit 2813b9c0296259fb11e75c839bab2d958ba4f96c).

Tag-based KASAN doesn't check memory accesses through pointers tagged with
0xff.  When page_address is used to get pointer to memory that corresponds
to some page, the tag of the resulting pointer gets set to 0xff, even
though the allocated memory might have been tagged differently.

For slab pages it's impossible to recover the correct tag to return from
page_address, since the page might contain multiple slab objects tagged
with different values, and we can't know in advance which one of them is
going to get accessed.  For non slab pages however, we can recover the tag
in page_address, since the whole page was marked with the same tag.

This patch adds tagging to non slab memory allocated with pagealloc.  To
set the tag of the pointer returned from page_address, the tag gets stored
to page->flags when the memory gets allocated.

Link: http://lkml.kernel.org/r/d758ddcef46a5abc9970182b9137e2fbee202a2c.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Bug: 128674696
Change-Id: I500bdf42462fee0ee14495a6be51815e7e44460f
This commit is contained in:
Andrey Konovalov
2018-12-28 00:30:57 -08:00
committed by Alistair Delva
parent fd535b3748
commit be21fa3044
7 changed files with 72 additions and 4 deletions
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15
mm/kasan/common.c
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@ -220,8 +220,15 @@ void kasan_unpoison_stack_above_sp_to(const void *watermark)
void kasan_alloc_pages(struct page *page, unsigned int order)
{
u8 tag;
unsigned long i;
if (unlikely(PageHighMem(page)))
return;
tag = random_tag();
for (i = 0; i < (1 << order); i++)
page_kasan_tag_set(page + i, tag);
kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
}
@ -319,6 +326,10 @@ struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
void kasan_poison_slab(struct page *page)
{
unsigned long i;
for (i = 0; i < (1 << compound_order(page)); i++)
page_kasan_tag_reset(page + i);
kasan_poison_shadow(page_address(page),
PAGE_SIZE << compound_order(page),
KASAN_KMALLOC_REDZONE);
@ -517,7 +528,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
page = virt_to_head_page(ptr);
if (unlikely(!PageSlab(page))) {
if (reset_tag(ptr) != page_address(page)) {
if (ptr != page_address(page)) {
kasan_report_invalid_free(ptr, ip);
return;
}
@ -530,7 +541,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
void kasan_kfree_large(void *ptr, unsigned long ip)
{
if (reset_tag(ptr) != page_address(virt_to_head_page(ptr)))
if (ptr != page_address(virt_to_head_page(ptr)))
kasan_report_invalid_free(ptr, ip);
/* The object will be poisoned by page_alloc. */
}