Return-path: Received: from mx1.redhat.com ([209.132.183.28]:38690 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759905AbdCVPIu (ORCPT ); Wed, 22 Mar 2017 11:08:50 -0400 From: Stanislaw Gruszka To: netdev@vger.kernel.org Cc: linux-wireless@vger.kernel.org, Stanislaw Gruszka , Xose Vazquez Perez , Larry Finger , Johannes Berg Subject: [PATCH 4.11] genetlink: fix counting regression on ctrl_dumpfamily() Date: Wed, 22 Mar 2017 16:08:33 +0100 Message-Id: <1490195313-13272-1-git-send-email-sgruszka@redhat.com> (sfid-20170322_160930_547274_B3A5EF84) Sender: linux-wireless-owner@vger.kernel.org List-ID: Commit 2ae0f17df1cd ("genetlink: use idr to track families") replaced if (++n < fams_to_skip) continue; into: if (n++ < fams_to_skip) continue; This subtle change cause that on retry ctrl_dumpfamily() call we omit one family that failed to do ctrl_fill_info() on previous call, because cb->args[0] = n number counts also family that failed to do ctrl_fill_info(). Patch fixes the problem and avoid confusion in the future just decrease n counter when ctrl_fill_info() fail. User visible problem caused by this bug is failure to get access to some genetlink family i.e. nl80211. However problem is reproducible only if number of registered genetlink families is big enough to cause second call of ctrl_dumpfamily(). Cc: Xose Vazquez Perez Cc: Larry Finger Cc: Johannes Berg Fixes: 2ae0f17df1cd ("genetlink: use idr to track families") Signed-off-by: Stanislaw Gruszka --- Dave, please also target this for 4.10+ -stable. net/netlink/genetlink.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index fb6e10f..92e0981 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -783,8 +783,10 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb) if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq, NLM_F_MULTI, - skb, CTRL_CMD_NEWFAMILY) < 0) + skb, CTRL_CMD_NEWFAMILY) < 0) { + n--; break; + } } cb->args[0] = n; -- 1.7.1