• Eric Dumazet's avatar
    bpf: devmap: fix use-after-free Read in __dev_map_entry_free · ddfe0bfd
    Eric Dumazet authored
    commit 2baae3545327632167c0180e9ca1d467416f1919 upstream.
    synchronize_rcu() is fine when the rcu callbacks only need
    to free memory (kfree_rcu() or direct kfree() call rcu call backs)
    __dev_map_entry_free() is a bit more complex, so we need to make
    sure that call queued __dev_map_entry_free() callbacks have completed.
    sysbot report:
    BUG: KASAN: use-after-free in dev_map_flush_old kernel/bpf/devmap.c:365
    BUG: KASAN: use-after-free in __dev_map_entry_free+0x2a8/0x300
    Read of size 8 at addr ffff8801b8da38c8 by task ksoftirqd/1/18
    CPU: 1 PID: 18 Comm: ksoftirqd/1 Not tainted 4.17.0+ #39
    Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
    Google 01/01/2011
    Call Trace:
      __dump_stack lib/dump_stack.c:77 [inline]
      dump_stack+0x1b9/0x294 lib/dump_stack.c:113
      print_address_description+0x6c/0x20b mm/kasan/report.c:256
      kasan_report_error mm/kasan/report.c:354 [inline]
      kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
      __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
      dev_map_flush_old kernel/bpf/devmap.c:365 [inline]
      __dev_map_entry_free+0x2a8/0x300 kernel/bpf/devmap.c:379
      __rcu_reclaim kernel/rcu/rcu.h:178 [inline]
      rcu_do_batch kernel/rcu/tree.c:2558 [inline]
      invoke_rcu_callbacks kernel/rcu/tree.c:2818 [inline]
      __rcu_process_callbacks kernel/rcu/tree.c:2785 [inline]
      rcu_process_callbacks+0xe9d/0x1760 kernel/rcu/tree.c:2802
      __do_softirq+0x2e0/0xaf5 kernel/softirq.c:284
      run_ksoftirqd+0x86/0x100 kernel/softirq.c:645
      smpboot_thread_fn+0x417/0x870 kernel/smpboot.c:164
      kthread+0x345/0x410 kernel/kthread.c:240
      ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
    Allocated by task 6675:
      save_stack+0x43/0xd0 mm/kasan/kasan.c:448
      set_track mm/kasan/kasan.c:460 [inline]
      kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
      kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
      kmalloc include/linux/slab.h:513 [inline]
      kzalloc include/linux/slab.h:706 [inline]
      dev_map_alloc+0x208/0x7f0 kernel/bpf/devmap.c:102
      find_and_alloc_map kernel/bpf/syscall.c:129 [inline]
      map_create+0x393/0x1010 kernel/bpf/syscall.c:453
      __do_sys_bpf kernel/bpf/syscall.c:2351 [inline]
      __se_sys_bpf kernel/bpf/syscall.c:2328 [inline]
      __x64_sys_bpf+0x303/0x510 kernel/bpf/syscall.c:2328
      do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290
    Freed by task 26:
      save_stack+0x43/0xd0 mm/kasan/kasan.c:448
      set_track mm/kasan/kasan.c:460 [inline]
      __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
      kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
      __cache_free mm/slab.c:3498 [inline]
      kfree+0xd9/0x260 mm/slab.c:3813
      dev_map_free+0x4fa/0x670 kernel/bpf/devmap.c:191
      bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262
      process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
      worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
      kthread+0x345/0x410 kernel/kthread.c:240
      ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
    The buggy address belongs to the object at ffff8801b8da37c0
      which belongs to the cache kmalloc-512 of size 512
    The buggy address is located 264 bytes inside of
      512-byte region [ffff8801b8da37c0, ffff8801b8da39c0)
    The buggy address belongs to the page:
    page:ffffea0006e368c0 count:1 mapcount:0 mapping:ffff8801da800940
    flags: 0x2fffc0000000100(slab)
    raw: 02fffc0000000100 ffffea0007217b88 ffffea0006e30cc8 ffff8801da800940
    raw: ffff8801b8da3540 ffff8801b8da3040 0000000100000004 0000000000000000
    page dumped because: kasan: bad access detected
    Memory state around the buggy address:
      ffff8801b8da3780: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
      ffff8801b8da3800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
    > ffff8801b8da3880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
      ffff8801b8da3900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
      ffff8801b8da3980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
    Fixes: 546ac1ff ("bpf: add devmap, a map for storing net device references")
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Reported-by: syzbot+457d3e2ffbcf31aee5c0@syzkaller.appspotmail.com
    Acked-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
    Acked-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
    Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
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