From 1d2a6a5e4bf2921531071fcff8538623dce74efa Mon Sep 17 00:00:00 2001 From: Stanislaw Gruszka Date: Wed, 22 Mar 2017 16:08:33 +0100 Subject: [PATCH] genetlink: fix counting regression on ctrl_dumpfamily() 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 Acked-by: Johannes Berg Signed-off-by: David S. Miller --- net/netlink/genetlink.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index fb6e10fdb217..92e0981f7404 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; -- 2.30.2