nl/mac80211: allow zero plink timeout to disable STA expiration

Both wpa_supplicant and mac80211 have and inactivity timer. By default
wpa_supplicant will be timed out in 5 minutes and mac80211's it is 30
minutes. If wpa_supplicant uses a longer timer than mac80211, it will
get unexpected disconnection by mac80211.

Using 0xffffffff instead as the configured value could solve this w/o
changing the code, but due to integer overflow in the expression used
this doesn't work. The expression is:

(current jiffies) > (frame Rx jiffies + NL80211_MESHCONF_PLINK_TIMEOUT * 250)

On 32bit system, the right side would overflow and be a very small
value if NL80211_MESHCONF_PLINK_TIMEOUT is sufficiently large,
causing unexpectedly early disconnections.

Instead allow disabling the inactivity timer to avoid this situation,
by passing the (previously invalid and useless) value 0.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>
[reword/rewrap commit log]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 3 insertions, 2 deletions

diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 0c8b2a77d312..acf441ff9f4a 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -574,7 +574,8 @@ static void ieee80211_mesh_housekeeping(struct ieee80211_sub_if_data *sdata)
         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
         u32 changed;
 
-        ieee80211_sta_expire(sdata, ifmsh->mshcfg.plink_timeout * HZ);
+        if (ifmsh->mshcfg.plink_timeout > 0)
+                ieee80211_sta_expire(sdata, ifmsh->mshcfg.plink_timeout * HZ);
         mesh_path_expire(sdata);
 
         changed = mesh_accept_plinks_update(sdata);
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index d78fd8b54515..9c6e23ede5b2 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -5265,7 +5265,7 @@ do {									    \
         FILL_IN_MESH_PARAM_IF_SET(tb, cfg, dot11MeshAwakeWindowDuration,
                                   0, 65535, mask,
                                   NL80211_MESHCONF_AWAKE_WINDOW, nla_get_u16);
-        FILL_IN_MESH_PARAM_IF_SET(tb, cfg, plink_timeout, 1, 0xffffffff,
+        FILL_IN_MESH_PARAM_IF_SET(tb, cfg, plink_timeout, 0, 0xffffffff,
                                   mask, NL80211_MESHCONF_PLINK_TIMEOUT,
                                   nla_get_u32);
         if (mask_out)