1. 17 Dec, 2018 1 commit
    • Jiri Wiesner's avatar
      ipv4: ipv6: netfilter: Adjust the frag mem limit when truesize changes · ffe5754d
      Jiri Wiesner authored
      [ Upstream commit ebaf39e6 ]
      
      The *_frag_reasm() functions are susceptible to miscalculating the byte
      count of packet fragments in case the truesize of a head buffer changes.
      The truesize member may be changed by the call to skb_unclone(), leaving
      the fragment memory limit counter unbalanced even if all fragments are
      processed. This miscalculation goes unnoticed as long as the network
      namespace which holds the counter is not destroyed.
      
      Should an attempt be made to destroy a network namespace that holds an
      unbalanced fragment memory limit counter the cleanup of the namespace
      never finishes. The thread handling the cleanup gets stuck in
      inet_frags_exit_net() waiting for the percpu counter to reach zero. The
      thread is usually in running state with a stacktrace similar to:
      
       PID: 1073   TASK: ffff880626711440  CPU: 1   COMMAND: "kworker/u48:4"
        #5 [ffff880621563d48] _raw_spin_lock at ffffffff815f5480
        #6 [ffff880621563d48] inet_evict_bucket at ffffffff8158020b
        #7 [ffff880621563d80] inet_frags_exit_net at ffffffff8158051c
        #8 [ffff880621563db0] ops_exit_list at ffffffff814f5856
        #9 [ffff880621563dd8] cleanup_net at ffffffff814f67c0
       #10 [ffff880621563e38] process_one_work at ffffffff81096f14
      
      It is not possible to create new network namespaces, and processes
      that call unshare() end up being stuck in uninterruptible sleep state
      waiting to acquire the net_mutex.
      
      The bug was observed in the IPv6 netfilter code by Per Sundstrom.
      I thank him for his analysis of the problem. The parts of this patch
      that apply to IPv4 and IPv6 fragment reassembly are preemptive measures.
      Signed-off-by: default avatarJiri Wiesner <jwiesner@suse.com>
      Reported-by: default avatarPer Sundstrom <per.sundstrom@redqube.se>
      Acked-by: default avatarPeter Oskolkov <posk@google.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      ffe5754d
  2. 13 Dec, 2018 39 commits