Messages in this thread Patch in this message | | | From | andrey.konovalov@linux ... | Subject | [PATCH mm v5 05/39] kasan, page_alloc: init memory of skipped pages on free | Date | Thu, 30 Dec 2021 20:12:07 +0100 |
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From: Andrey Konovalov <andreyknvl@google.com>
Since commit 7a3b83537188 ("kasan: use separate (un)poison implementation for integrated init"), when all init, kasan_has_integrated_init(), and skip_kasan_poison are true, free_pages_prepare() doesn't initialize the page. This is wrong.
Fix it by remembering whether kasan_poison_pages() performed initialization, and call kernel_init_free_pages() if it didn't.
Reordering kasan_poison_pages() and kernel_init_free_pages() is OK, since kernel_init_free_pages() can handle poisoned memory.
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
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Changes v2->v3: - Drop Fixes tag, as the patch won't cleanly apply to older kernels anyway. The commit is mentioned in the patch description.
Changes v1->v2: - Reorder kasan_poison_pages() and free_pages_prepare() in this patch instead of doing it in the previous one. --- mm/page_alloc.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f78058115288..37e121ff99b1 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1375,11 +1375,16 @@ static __always_inline bool free_pages_prepare(struct page *page, * With hardware tag-based KASAN, memory tags must be set before the * page becomes unavailable via debug_pagealloc or arch_free_page. */ - if (init && !kasan_has_integrated_init()) - kernel_init_free_pages(page, 1 << order); - if (!skip_kasan_poison) + if (!skip_kasan_poison) { kasan_poison_pages(page, order, init); + /* Memory is already initialized if KASAN did it internally. */ + if (kasan_has_integrated_init()) + init = false; + } + if (init) + kernel_init_free_pages(page, 1 << order); + /* * arch_free_page() can make the page's contents inaccessible. s390 * does this. So nothing which can access the page's contents should -- 2.25.1
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