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From: Stanislaw Gruszka <sgruszka@redhat.com>
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Date: 2017-03-22 15:08:33
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Subject: [PATCH 4.11] genetlink: fix counting regression on ctrl_dumpfamily()
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Commit 2ae0f17df1cd ("genetlink: use idr to track families") replaced
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if (++n < fams_to_skip)
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continue;
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into:
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if (n++ < fams_to_skip)
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continue;
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This subtle change cause that on retry ctrl_dumpfamily() call we omit
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one family that failed to do ctrl_fill_info() on previous call, because
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cb->args[0] = n number counts also family that failed to do
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ctrl_fill_info().
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Patch fixes the problem and avoid confusion in the future just decrease
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n counter when ctrl_fill_info() fail.
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User visible problem caused by this bug is failure to get access to
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some genetlink family i.e. nl80211. However problem is reproducible
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only if number of registered genetlink families is big enough to
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cause second call of ctrl_dumpfamily().
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Cc: Xose Vazquez Perez <xose.vazquez@gmail.com>
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Cc: Larry Finger <Larry.Finger@lwfinger.net>
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Cc: Johannes Berg <johannes@sipsolutions.net>
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Fixes: 2ae0f17df1cd ("genetlink: use idr to track families")
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Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
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---
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Dave, please also target this for 4.10+ -stable.
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net/netlink/genetlink.c | 4 +++-
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1 files changed, 3 insertions(+), 1 deletions(-)
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diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
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index fb6e10f..92e0981 100644
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--- a/net/netlink/genetlink.c
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+++ b/net/netlink/genetlink.c
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@@ -783,8 +783,10 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb)
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if (ctrl_fill_info(rt, NETLINK_CB(cb->skb).portid,
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cb->nlh->nlmsg_seq, NLM_F_MULTI,
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- skb, CTRL_CMD_NEWFAMILY) < 0)
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+ skb, CTRL_CMD_NEWFAMILY) < 0) {
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+ n--;
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break;
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+ }
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}
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cb->args[0] = n;
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--
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1.7.1
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