From: Michal Kazior <michal@xxxxxxxxx> [ Upstream commit a6e4f85d3820d00694ed10f581f4c650445dbcda ] The nl80211_dump_interface() supports resumption in case nl80211_send_iface() doesn't have the resources to complete its work. The logic would store the progress as iteration offsets for rdev and wdev loops. However the logic did not properly handle resumption for non-last rdev. Assuming a system with 2 rdevs, with 2 wdevs each, this could happen: dump(cb=[0, 0]): if_start=cb[1] (=0) send rdev0.wdev0 -> ok send rdev0.wdev1 -> yield cb[1] = 1 dump(cb=[0, 1]): if_start=cb[1] (=1) send rdev0.wdev1 -> ok // since if_start=1 the rdev0.wdev0 got skipped // through if_idx < if_start send rdev1.wdev1 -> ok The if_start needs to be reset back to 0 upon wdev loop end. The problem is actually hard to hit on a desktop, and even on most routers. The prerequisites for this manifesting was: - more than 1 wiphy - a few handful of interfaces - dump without rdev or wdev filter I was seeing this with 4 wiphys 9 interfaces each. It'd miss 6 interfaces from the last wiphy reported to userspace. Signed-off-by: Michal Kazior <michal@xxxxxxxxx> Link: https://msgid.link/20240116142340.89678-1-kazikcz@xxxxxxxxx Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/wireless/nl80211.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index e33c1175b158..f79700e5d801 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -2994,6 +2994,7 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback * if_idx++; } + if_start = 0; wp_idx++; } out: -- 2.43.0
