lkml.org 
[lkml]   [2022]   [Jan]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.16 0830/1039] kasan: fix quarantine conflicting with init_on_free
    Date
    From: Andrey Konovalov <andreyknvl@google.com>

    [ Upstream commit 26dca996ea7b1ac7008b6b6063fc88b849e3ac3e ]

    KASAN's quarantine might save its metadata inside freed objects. As
    this happens after the memory is zeroed by the slab allocator when
    init_on_free is enabled, the memory coming out of quarantine is not
    properly zeroed.

    This causes lib/test_meminit.c tests to fail with Generic KASAN.

    Zero the metadata when the object is removed from quarantine.

    Link: https://lkml.kernel.org/r/2805da5df4b57138fdacd671f5d227d58950ba54.1640037083.git.andreyknvl@google.com
    Fixes: 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options")
    Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    Reviewed-by: Marco Elver <elver@google.com>
    Cc: Alexander Potapenko <glider@google.com>
    Cc: Andrey Konovalov <andreyknvl@gmail.com>
    Cc: Dmitry Vyukov <dvyukov@google.com>
    Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    mm/kasan/quarantine.c | 11 +++++++++++
    1 file changed, 11 insertions(+)

    diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
    index d8ccff4c1275e..47ed4fc33a29e 100644
    --- a/mm/kasan/quarantine.c
    +++ b/mm/kasan/quarantine.c
    @@ -132,11 +132,22 @@ static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
    static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
    {
    void *object = qlink_to_object(qlink, cache);
    + struct kasan_free_meta *meta = kasan_get_free_meta(cache, object);
    unsigned long flags;

    if (IS_ENABLED(CONFIG_SLAB))
    local_irq_save(flags);

    + /*
    + * If init_on_free is enabled and KASAN's free metadata is stored in
    + * the object, zero the metadata. Otherwise, the object's memory will
    + * not be properly zeroed, as KASAN saves the metadata after the slab
    + * allocator zeroes the object.
    + */
    + if (slab_want_init_on_free(cache) &&
    + cache->kasan_info.free_meta_offset == 0)
    + memzero_explicit(meta, sizeof(*meta));
    +
    /*
    * As the object now gets freed from the quarantine, assume that its
    * free track is no longer valid.
    --
    2.34.1


    \
     
     \ /
      Last update: 2022-01-25 00:11    [W:2.572 / U:0.092 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site