mac80211: use a counter for remain-on-channel cookie

Instead of using the pointer which can be re-used
fairly quickly due to allocator patterns and then
makes debugging difficult, maintain a counter and
use its value. Since it's a 64-bit value it can't
really wrap, but catch that case anyway since it
most likely points to a bug somewhere.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 20 insertions, 11 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 986e9a139d42..eebb70b0aa11 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2382,13 +2382,22 @@ static int ieee80211_start_roc_work(struct ieee80211_local *local,
                 list_add_tail(&roc->list, &local->roc_list);
 
         /*
-         * cookie is either the roc (for normal roc)
+         * cookie is either the roc cookie (for normal roc)
          * or the SKB (for mgmt TX)
          */
-        if (txskb)
+        if (!txskb) {
+                /* local->mtx protects this */
+                local->roc_cookie_counter++;
+                roc->cookie = local->roc_cookie_counter;
+                /* wow, you wrapped 64 bits ... more likely a bug */
+                if (WARN_ON(roc->cookie == 0)) {
+                        roc->cookie = 1;
+                        local->roc_cookie_counter++;
+                }
+                *cookie = roc->cookie;
+        } else {
                 *cookie = (unsigned long)txskb;
-        else
-                *cookie = (unsigned long)roc;
+        }
 
         return 0;
 }
@@ -2423,7 +2432,7 @@ static int ieee80211_cancel_roc(struct ieee80211_local *local,
                 struct ieee80211_roc_work *dep, *tmp2;
 
                 list_for_each_entry_safe(dep, tmp2, &roc->dependents, list) {
-                        if (!mgmt_tx && (unsigned long)dep != cookie)
+                        if (!mgmt_tx && dep->cookie != cookie)
                                 continue;
                         else if (mgmt_tx && dep->mgmt_tx_cookie != cookie)
                                 continue;
@@ -2435,7 +2444,7 @@ static int ieee80211_cancel_roc(struct ieee80211_local *local,
                         return 0;
                 }
 
-                if (!mgmt_tx && (unsigned long)roc != cookie)
+                if (!mgmt_tx && roc->cookie != cookie)
                         continue;
                 else if (mgmt_tx && roc->mgmt_tx_cookie != cookie)
                         continue;
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a1f7c139308e..d272e0cabc37 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -356,7 +356,7 @@ struct ieee80211_roc_work {
 
         u32 duration, req_duration;
         struct sk_buff *frame;
-        u64 mgmt_tx_cookie;
+        u64 cookie, mgmt_tx_cookie;
 };
 
 /* flags used in struct ieee80211_if_managed.flags */
@@ -1142,6 +1142,7 @@ struct ieee80211_local {
         struct list_head roc_list;
         struct work_struct hw_roc_start, hw_roc_done;
         unsigned long hw_roc_start_time;
+        u64 roc_cookie_counter;
 
         struct idr ack_status_frames;
         spinlock_t ack_status_lock;
diff --git a/net/mac80211/offchannel.c b/net/mac80211/offchannel.c
index c349f3aaf59e..0cd42d52880c 100644
--- a/net/mac80211/offchannel.c
+++ b/net/mac80211/offchannel.c
@@ -204,7 +204,7 @@ void ieee80211_handle_roc_started(struct ieee80211_roc_work *roc)
                         roc->frame = NULL;
                 }
         } else {
-                cfg80211_ready_on_channel(&roc->sdata->wdev, (unsigned long)roc,
+                cfg80211_ready_on_channel(&roc->sdata->wdev, roc->cookie,
                                           roc->chan, roc->chan_type,
                                           roc->req_duration, GFP_KERNEL);
         }
@@ -320,9 +320,8 @@ void ieee80211_roc_notify_destroy(struct ieee80211_roc_work *roc)
 
         if (!roc->mgmt_tx_cookie)
                 cfg80211_remain_on_channel_expired(&roc->sdata->wdev,
-                                                   (unsigned long)roc,
-                                                   roc->chan, roc->chan_type,
-                                                   GFP_KERNEL);
+                                                   roc->cookie, roc->chan,
+                                                   roc->chan_type, GFP_KERNEL);
 
         list_for_each_entry_safe(dep, tmp, &roc->dependents, list)
                 ieee80211_roc_notify_destroy(dep);