1. 28 Feb, 2018 1 commit
    • Paolo Abeni's avatar
      netfilter: drop outermost socket lock in getsockopt() · 482526ec
      Paolo Abeni authored
      commit 01ea306f upstream.
      
      The Syzbot reported a possible deadlock in the netfilter area caused by
      rtnl lock, xt lock and socket lock being acquired with a different order
      on different code paths, leading to the following backtrace:
      Reviewed-by: default avatarXin Long <lucien.xin@gmail.com>
      
      ======================================================
      WARNING: possible circular locking dependency detected
      4.15.0+ #301 Not tainted
      ------------------------------------------------------
      syzkaller233489/4179 is trying to acquire lock:
        (rtnl_mutex){+.+.}, at: [<0000000048e996fd>] rtnl_lock+0x17/0x20
      net/core/rtnetlink.c:74
      
      but task is already holding lock:
        (&xt[i].mutex){+.+.}, at: [<00000000328553a2>]
      xt_find_table_lock+0x3e/0x3e0 net/netfilter/x_tables.c:1041
      
      which lock already depends on the new lock.
      ===
      
      Since commit 3f34cfae1230 ("netfilter: on sockopt() acquire sock lock
      only in the required scope"), we already acquire the socket lock in
      the innermost scope, where needed. In such commit I forgot to remove
      the outer-most socket lock from the getsockopt() path, this commit
      addresses the issues dropping it now.
      
      v1 -> v2: fix bad subj, added relavant 'fixes' tag
      
      Fixes: 22265a5c ("netfilter: xt_TEE: resolve oif using netdevice notifiers")
      Fixes: 202f59af ("netfilter: ipt_CLUSTERIP: do not hold dev")
      Fixes: 3f34cfae1230 ("netfilter: on sockopt() acquire sock lock only in the required scope")
      Reported-by: syzbot+ddde1c7b7ff7442d7f2d@syzkaller.appspotmail.com
      Suggested-by: default avatarFlorian Westphal <fw@strlen.de>
      Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
      Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
      Tested-by: default avatarKrzysztof Piotr Oledzki <ole@ans.pl>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      482526ec
  2. 25 Feb, 2018 39 commits