1. 09 Mar, 2018 35 commits
  2. 03 Mar, 2018 5 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.14.24 · 6e4548ea
      Greg Kroah-Hartman authored
      6e4548ea
    • Jiri Pirko's avatar
      net: sched: fix use-after-free in tcf_block_put_ext · ab5d9d17
      Jiri Pirko authored
      commit df45bf84 upstream.
      
      Since the block is freed with last chain being put, once we reach the
      end of iteration of list_for_each_entry_safe, the block may be
      already freed. I'm hitting this only by creating and deleting clsact:
      
      [  202.171952] ==================================================================
      [  202.180182] BUG: KASAN: use-after-free in tcf_block_put_ext+0x240/0x390
      [  202.187590] Read of size 8 at addr ffff880225539a80 by task tc/796
      [  202.194508]
      [  202.196185] CPU: 0 PID: 796 Comm: tc Not tainted 4.15.0-rc2jiri+ #5
      [  202.203200] Hardware name: Mellanox Technologies Ltd. "MSN2100-CB2F"/"SA001017", BIOS 5.6.5 06/07/2016
      [  202.213613] Call Trace:
      [  202.216369]  dump_stack+0xda/0x169
      [  202.220192]  ? dma_virt_map_sg+0x147/0x147
      [  202.224790]  ? show_regs_print_info+0x54/0x54
      [  202.229691]  ? tcf_chain_destroy+0x1dc/0x250
      [  202.234494]  print_address_description+0x83/0x3d0
      [  202.239781]  ? tcf_block_put_ext+0x240/0x390
      [  202.244575]  kasan_report+0x1ba/0x460
      [  202.248707]  ? tcf_block_put_ext+0x240/0x390
      [  202.253518]  tcf_block_put_ext+0x240/0x390
      [  202.258117]  ? tcf_chain_flush+0x290/0x290
      [  202.262708]  ? qdisc_hash_del+0x82/0x1a0
      [  202.267111]  ? qdisc_hash_add+0x50/0x50
      [  202.271411]  ? __lock_is_held+0x5f/0x1a0
      [  202.275843]  clsact_destroy+0x3d/0x80 [sch_ingress]
      [  202.281323]  qdisc_destroy+0xcb/0x240
      [  202.285445]  qdisc_graft+0x216/0x7b0
      [  202.289497]  tc_get_qdisc+0x260/0x560
      
      Fix this by holding the block also by chain 0 and put chain 0
      explicitly, out of the list_for_each_entry_safe loop at the very
      end of tcf_block_put_ext.
      
      Fixes: efbf7897 ("net_sched: get rid of rcu_barrier() in tcf_block_put_ext()")
      Signed-off-by: default avatarJiri Pirko <jiri@mellanox.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Cong Wang <xiyou.wangcong@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      
      ab5d9d17
    • Cong Wang's avatar
      net_sched: get rid of rcu_barrier() in tcf_block_put_ext() · ac2be03b
      Cong Wang authored
      commit efbf7897 upstream.
      
      Both Eric and Paolo noticed the rcu_barrier() we use in
      tcf_block_put_ext() could be a performance bottleneck when
      we have a lot of tc classes.
      
      Paolo provided the following to demonstrate the issue:
      
      tc qdisc add dev lo root htb
      for I in `seq 1 1000`; do
              tc class add dev lo parent 1: classid 1:$I htb rate 100kbit
              tc qdisc add dev lo parent 1:$I handle $((I + 1)): htb
              for J in `seq 1 10`; do
                      tc filter add dev lo parent $((I + 1)): u32 match ip src 1.1.1.$J
              done
      done
      time tc qdisc del dev root
      
      real    0m54.764s
      user    0m0.023s
      sys     0m0.000s
      
      The rcu_barrier() there is to ensure we free the block after all chains
      are gone, that is, to queue tcf_block_put_final() at the tail of workqueue.
      We can achieve this ordering requirement by refcnt'ing tcf block instead,
      that is, the tcf block is freed only when the last chain in this block is
      gone. This also simplifies the code.
      
      Paolo reported after this patch we get:
      
      real    0m0.017s
      user    0m0.000s
      sys     0m0.017s
      Tested-by: default avatarPaolo Abeni <pabeni@redhat.com>
      Cc: Eric Dumazet <edumazet@google.com>
      Cc: Jiri Pirko <jiri@mellanox.com>
      Cc: Jamal Hadi Salim <jhs@mojatatu.com>
      Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      
      ac2be03b
    • Roman Kapl's avatar
      net: sched: crash on blocks with goto chain action · 1c8e7e61
      Roman Kapl authored
      commit a60b3f51 upstream.
      
      tcf_block_put_ext has assumed that all filters (and thus their goto
      actions) are destroyed in RCU callback and thus can not race with our
      list iteration. However, that is not true during netns cleanup (see
      tcf_exts_get_net comment).
      
      Prevent the user after free by holding all chains (except 0, that one is
      already held). foreach_safe is not enough in this case.
      
      To reproduce, run the following in a netns and then delete the ns:
          ip link add dtest type dummy
          tc qdisc add dev dtest ingress
          tc filter add dev dtest chain 1 parent ffff: handle 1 prio 1 flower action goto chain 2
      
      Fixes: 822e86d9 ("net_sched: remove tcf_block_put_deferred()")
      Signed-off-by: default avatarRoman Kapl <code@rkapl.cz>
      Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Cong Wang <xiyou.wangcong@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1c8e7e61
    • Roman Kapl's avatar
      net: sched: fix crash when deleting secondary chains · b6b42b3d
      Roman Kapl authored
      commit d7aa04a5 upstream.
      
      If you flush (delete) a filter chain other than chain 0 (such as when
      deleting the device), the kernel may run into a use-after-free. The
      chain refcount must not be decremented unless we are sure we are done
      with the chain.
      
      To reproduce the bug, run:
          ip link add dtest type dummy
          tc qdisc add dev dtest ingress
          tc filter add dev dtest chain 1  parent ffff: flower
          ip link del dtest
      
      Introduced in: commit f93e1cdc ("net/sched: fix filter flushing"),
      but unless you have KAsan or luck, you won't notice it until
      commit 0dadc117 ("cls_flower: use tcf_exts_get_net() before call_rcu()")
      
      Fixes: f93e1cdc ("net/sched: fix filter flushing")
      Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
      Signed-off-by: default avatarRoman Kapl <code@rkapl.cz>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Cc: Cong Wang <xiyou.wangcong@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b6b42b3d