mac80211: fix vif name tracing

If sdata doesn't have a valid dev (e.g. in case of monitor
vif), the vif_name field was initialized with (a length of)
some short string, but later was set to a different,
potentially larger one.

This resulted in out-of-bounds write, which usually
appeared as garbage in the trace log.

Simply trace sdata->name, as it should always have the
correct name for both cases.
Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/trace.h

@@ -21,10 +21,10 @@
 
 #define VIF_ENTRY	__field(enum nl80211_iftype, vif_type) __field(void *, sdata)	\
 			__field(bool, p2p)						\
-			__string(vif_name, sdata->dev ? sdata->dev->name : "<nodev>")
+			__string(vif_name, sdata->name)
 #define VIF_ASSIGN	__entry->vif_type = sdata->vif.type; __entry->sdata = sdata;	\
 			__entry->p2p = sdata->vif.p2p;					\
-			__assign_str(vif_name, sdata->dev ? sdata->dev->name : sdata->name)
+			__assign_str(vif_name, sdata->name)
 #define VIF_PR_FMT	" vif:%s(%d%s)"
 #define VIF_PR_ARG	__get_str(vif_name), __entry->vif_type, __entry->p2p ? "/p2p" : ""