lkml.org 
[lkml]   [2021]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH mm v4 05/39] kasan, page_alloc: init memory of skipped pages on free
    Date
    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>

    ---

    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 db8cecdd0aaa..114d6b010331 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -1374,11 +1374,16 @@ 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
    \
     
     \ /
      Last update: 2021-12-20 23:00    [W:4.083 / U:0.108 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site