[patch 09/12] mac80211: fix iff_promiscs, iff_allmultis race
From: Johannes Berg <johannes@sipsolutions.net>
Date: 2007-09-26 13:25:09
When we update the counters iff_promiscs and iff_allmultis in struct ieee80211_local we have no common lock held to protect them. The problem is that the update to each counter may not be atomic, so we could end up with iff_promiscs == -1 in unfortunate conditions. To fix it, use atomic_t values. It doesn't matter whether the two counters are updated together atomically or not, if there are two invocations of set_multicast_list we will end up with multiple configure_filter() invocations of which the latter will always be correct. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> --- net/mac80211/ieee80211.c | 12 ++++++------ net/mac80211/ieee80211_i.h | 5 ++--- net/mac80211/rx.c | 3 ++- 3 files changed, 10 insertions(+), 10 deletions(-)
--- wireless-dev.orig/net/mac80211/ieee80211.c 2007-09-25 23:29:36.561571777 +0200
+++ wireless-dev/net/mac80211/ieee80211.c 2007-09-25 23:29:39.261570204 +0200@@ -59,10 +59,10 @@ static void ieee80211_configure_filter(s unsigned int changed_flags; unsigned int new_flags = 0; - if (local->iff_promiscs) + if (atomic_read(&local->iff_promiscs)) new_flags |= FIF_PROMISC_IN_BSS; - if (local->iff_allmultis) + if (atomic_read(&local->iff_allmultis)) new_flags |= FIF_ALLMULTI; if (local->monitors)
@@ -522,17 +522,17 @@ static void ieee80211_set_multicast_list if (allmulti != sdata_allmulti) { if (dev->flags & IFF_ALLMULTI) - local->iff_allmultis++; + atomic_inc(&local->iff_allmultis); else - local->iff_allmultis--; + atomic_dec(&local->iff_allmultis); sdata->flags ^= IEEE80211_SDATA_ALLMULTI; } if (promisc != sdata_promisc) { if (dev->flags & IFF_PROMISC) - local->iff_promiscs++; + atomic_inc(&local->iff_promiscs); else - local->iff_promiscs--; + atomic_dec(&local->iff_promiscs); sdata->flags ^= IEEE80211_SDATA_PROMISC; } --- wireless-dev.orig/net/mac80211/ieee80211_i.h 2007-09-25 23:29:37.921572374 +0200 +++ wireless-dev/net/mac80211/ieee80211_i.h 2007-09-25 23:29:39.261570204 +0200
@@ -444,9 +444,8 @@ struct ieee80211_local { struct ieee80211_tx_stored_packet pending_packet[NUM_TX_DATA_QUEUES]; struct tasklet_struct tx_pending_tasklet; - int mc_count; /* total count of multicast entries in all interfaces */ - int iff_allmultis, iff_promiscs; - /* number of interfaces with corresponding IFF_ flags */ + /* number of interfaces with corresponding IFF_ flags */ + atomic_t iff_allmultis, iff_promiscs; struct rate_control_ref *rate_ctrl; --- wireless-dev.orig/net/mac80211/rx.c 2007-09-25 23:29:36.571573405 +0200 +++ wireless-dev/net/mac80211/rx.c 2007-09-25 23:29:39.271572319 +0200
@@ -1531,7 +1531,8 @@ void __ieee80211_rx(struct ieee80211_hw skb = rx.skb; if (sta && !(sta->flags & (WLAN_STA_WDS | WLAN_STA_ASSOC_AP)) && - !local->iff_promiscs && !is_multicast_ether_addr(hdr->addr1)) { + !atomic_read(&local->iff_promiscs) && + !is_multicast_ether_addr(hdr->addr1)) { rx.flags |= IEEE80211_TXRXD_RXRA_MATCH; ieee80211_invoke_rx_handlers(local, local->rx_handlers, &rx, rx.sta);
--