1. 25 Oct, 2019 1 commit
    • Pavel Shilovsky's avatar
      CIFS: Fix retry mid list corruption on reconnects · abe57073
      Pavel Shilovsky authored
      When the client hits reconnect it iterates over the mid
      pending queue marking entries for retry and moving them
      to a temporary list to issue callbacks later without holding
      GlobalMid_Lock. In the same time there is no guarantee that
      mids can't be removed from the temporary list or even
      freed completely by another thread. It may cause a temporary
      list corruption:
      
      [  430.454897] list_del corruption. prev->next should be ffff98d3a8f316c0, but was 2e885cb266355469
      [  430.464668] ------------[ cut here ]------------
      [  430.466569] kernel BUG at lib/list_debug.c:51!
      [  430.468476] invalid opcode: 0000 [#1] SMP PTI
      [  430.470286] CPU: 0 PID: 13267 Comm: cifsd Kdump: loaded Not tainted 5.4.0-rc3+ #19
      [  430.473472] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
      [  430.475872] RIP: 0010:__list_del_entry_valid.cold+0x31/0x55
      ...
      [  430.510426] Call Trace:
      [  430.511500]  cifs_reconnect+0x25e/0x610 [cifs]
      [  430.513350]  cifs_readv_from_socket+0x220/0x250 [cifs]
      [  430.515464]  cifs_read_from_socket+0x4a/0x70 [cifs]
      [  430.517452]  ? try_to_wake_up+0x212/0x650
      [  430.519122]  ? cifs_small_buf_get+0x16/0x30 [cifs]
      [  430.521086]  ? allocate_buffers+0x66/0x120 [cifs]
      [  430.523019]  cifs_demultiplex_thread+0xdc/0xc30 [cifs]
      [  430.525116]  kthread+0xfb/0x130
      [  430.526421]  ? cifs_handle_standard+0x190/0x190 [cifs]
      [  430.528514]  ? kthread_park+0x90/0x90
      [  430.530019]  ret_from_fork+0x35/0x40
      
      Fix this by obtaining extra references for mids being retried
      and marking them as MID_DELETED which indicates that such a mid
      has been dequeued from the pending list.
      
      Also move mid cleanup logic from DeleteMidQEntry to
      _cifs_mid_q_entry_release which is called when the last reference
      to a particular mid is put. This allows to avoid any use-after-free
      of response buffers.
      
      The patch needs to be backported to stable kernels. A stable tag
      is not mentioned below because the patch doesn't apply cleanly
      to any actively maintained stable kernel.
      Reviewed-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
      Reviewed-and-tested-by: default avatarDavid Wysochanski <dwysocha@redhat.com>
      Signed-off-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
      Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
      abe57073
  2. 21 Oct, 2019 4 commits
  3. 20 Oct, 2019 6 commits
  4. 19 Oct, 2019 29 commits