• Wang Hai's avatar
    mm/memcg: fix NULL pointer dereference in memcg_slab_free_hook() · 121dffe2
    Wang Hai authored
    When I use kfree_rcu() to free a large memory allocated by kmalloc_node(),
    the following dump occurs.
    
      BUG: kernel NULL pointer dereference, address: 0000000000000020
      [...]
      Oops: 0000 [#1] SMP
      [...]
      Workqueue: events kfree_rcu_work
      RIP: 0010:__obj_to_index include/linux/slub_def.h:182 [inline]
      RIP: 0010:obj_to_index include/linux/slub_def.h:191 [inline]
      RIP: 0010:memcg_slab_free_hook+0x120/0x260 mm/slab.h:363
      [...]
      Call Trace:
        kmem_cache_free_bulk+0x58/0x630 mm/slub.c:3293
        kfree_bulk include/linux/slab.h:413 [inline]
        kfree_rcu_work+0x1ab/0x200 kernel/rcu/tree.c:3300
        process_one_work+0x207/0x530 kernel/workqueue.c:2276
        worker_thread+0x320/0x610 kernel/workqueue.c:2422
        kthread+0x13d/0x160 kernel/kthread.c:313
        ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
    
    When kmalloc_node() a large memory, page is allocated, not slab, so when
    freeing memory via kfree_rcu(), this large memory should not be used by
    memcg_slab_free_hook(), because memcg_slab_free_hook() is is used for
    slab.
    
    Using page_objcgs_check() instead of page_objcgs() in
    memcg_slab_free_hook() to fix this bug.
    
    Link: https://lkml.kernel.org/r/20210728145655.274476-1-wanghai38@huawei.com
    Fixes: 270c6a71 ("mm: memcontrol/slab: Use helpers to access slab page's memcg_data")
    Signed-off-by: default avatarWang Hai <wanghai38@huawei.com>
    Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
    Acked-by: default avatarMichal Hocko <mhocko@suse.com>
    Acked-by: default avatarRoman Gushchin <guro@fb.com>
    Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
    Reviewed-by: default avatarMuchun Song <songmuchun@bytedance.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Alexei Starovoitov <ast@kernel.org>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    121dffe2
slab.h 17.3 KB