The patch titled
Subject: mm, kasan: fix to call kasan_free_pages() after poisoning page
has been added to the -mm tree. Its filename is
mm-kasan-fix-to-call-kasan_free_pages-after-poisoning-page.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-kasan-fix-to-call-kasan_free_pages-after-poisoning-page.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-kasan-fix-to-call-kasan_free_pages-after-poisoning-page.patch
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------------------------------------------------------
From: "seokhoon.yoon" <iamyooon@xxxxxxxxx>
Subject: mm, kasan: fix to call kasan_free_pages() after poisoning page
When CONFIG_PAGE_POISONING and CONFIG_KASAN is enabled,
free_pages_prepare()'s codeflow is below.
1)kmemcheck_free_shadow()
2)kasan_free_pages()
- set shadow byte of page is freed
3)kernel_poison_pages()
3.1) check access to page is valid or not using kasan
---> error occur, kasan think it is invalid access
3.2) poison page
4)kernel_map_pages()
So kasan_free_pages() should be called after poisoning the page.
Link: http://lkml.kernel.org/r/1463220405-7455-1-git-send-email-iamyooon@xxxxxxxxx
Signed-off-by: seokhoon.yoon <iamyooon@xxxxxxxxx>
Cc: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-kasan-fix-to-call-kasan_free_pages-after-poisoning-page mm/page_alloc.c
--- a/mm/page_alloc.c~mm-kasan-fix-to-call-kasan_free_pages-after-poisoning-page
+++ a/mm/page_alloc.c
@@ -993,7 +993,6 @@ static __always_inline bool free_pages_p
trace_mm_page_free(page, order);
kmemcheck_free_shadow(page, order);
- kasan_free_pages(page, order);
/*
* Check tail pages before head page information is cleared to
@@ -1035,6 +1034,7 @@ static __always_inline bool free_pages_p
arch_free_page(page, order);
kernel_poison_pages(page, 1 << order, 0);
kernel_map_pages(page, 1 << order, 0);
+ kasan_free_pages(page, order);
return true;
}
_
Patches currently in -mm which might be from iamyooon@xxxxxxxxx are
mm-kasan-fix-to-call-kasan_free_pages-after-poisoning-page.patch
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