[PATCH net] xdp: xdp_mem_allocator can be NULL in trace_mem_connect().

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

Since the commit mentioned below __xdp_reg_mem_model() can return a NULL
pointer. This pointer is dereferenced in trace_mem_connect() which leads
to segfault. It can be reproduced with enabled trace events during ifup.

Only assign the arguments in the trace-event macro if `xa' is set.
Otherwise set the parameters to 0.

Fixes: 4a48ef70b93b8 ("xdp: Allow registering memory model without rxq reference")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 include/trace/events/xdp.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index c40fc97f94171..9196dcd08e6c7 100644
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h
@@ -362,9 +362,9 @@ TRACE_EVENT(mem_connect,
 
 	TP_fast_assign(
 		__entry->xa		= xa;
-		__entry->mem_id		= xa->mem.id;
-		__entry->mem_type	= xa->mem.type;
-		__entry->allocator	= xa->allocator;
+		__entry->mem_id		= xa ? xa->mem.id : 0;
+		__entry->mem_type	= xa ? xa->mem.type : 0;
+		__entry->allocator	= xa ? xa->allocator : NULL;
 		__entry->rxq		= rxq;
 		__entry->ifindex	= rxq->dev->ifindex;
 	),
-- 
2.35.1