With the recent additions of new features, non-split phy dumps exceed the maximum Netlink size of 4096 bytes. Depending on their feature set, not all radios are affected, but for example hwsim is. While userspace dumping phys can request a split dump as a work around, legacy tools without split support may get oversized dumps. Much more problematic are phy new/del notifications, which are always limited to a page size: Generating these messages fails, and Netlink notifications are silently dropped. This breaks userspace relying on these events. There is no single commit that broke these events, as their size highly depends on the phy feature set. Finding attributes to strip is challenging: The largest attributes are the frequency lists, but they are already reduced to the minimum and have rather useful information. HE information probably could be stripped, but the saving is about 200 bytes, not enough to fix dumps for many cases. The next larger attributes are usually the RX/TX frame attributes. Removing these attributes can reduce a hwsim phy dump from 4576 to 3288 bytes, and it seems to be the most reasonable approach. This fixes Netlink phy notifications, but obviously removes supported RX/TX frames from these events and non-split phy dumps. Userspace is required to use split dumps to receive supported RX/TX frame information. Signed-off-by: Martin Willi <martin@xxxxxxxxxxxxxx> --- net/wireless/nl80211.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index 201d029687cc..9362fa407933 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -2304,7 +2304,7 @@ static int nl80211_send_wiphy(struct cfg80211_registered_device *rdev, nla_put_flag(msg, NL80211_ATTR_OFFCHANNEL_TX_OK)) goto nla_put_failure; - if (nl80211_send_mgmt_stypes(msg, mgmt_stypes)) + if (state->split && nl80211_send_mgmt_stypes(msg, mgmt_stypes)) goto nla_put_failure; state->split_start++; if (state->split) -- 2.25.1
