net: atlantic: add check for MAX_SKB_FRAGS

Enforce that the CPU can not get stuck in an infinite loop.
Reported-by: Aashay Shringarpure <aashay@google.com>
Reported-by: Yi Chou <yich@google.com>
Reported-by: Shervin Oloumi <enlightened@google.com>
Signed-off-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/aq_ring.c

@@ -363,6 +363,7 @@ int aq_ring_rx_clean(struct aq_ring_s *self,
 			continue;
 
 		if (!buff->is_eop) {
+			unsigned int frag_cnt = 0U;
 			buff_ = buff;
 			do {
 				bool is_rsc_completed = true;
@@ -371,6 +372,8 @@ int aq_ring_rx_clean(struct aq_ring_s *self,
 					err = -EIO;
 					goto err_exit;
 				}
+
+				frag_cnt++;
 				next_ = buff_->next,
 				buff_ = &self->buff_ring[next_];
 				is_rsc_completed =
@@ -378,7 +381,8 @@ int aq_ring_rx_clean(struct aq_ring_s *self,
 							    next_,
 							    self->hw_head);
 
-				if (unlikely(!is_rsc_completed)) {
+				if (unlikely(!is_rsc_completed) ||
+						frag_cnt > MAX_SKB_FRAGS) {
 					err = 0;
 					goto err_exit;
 				}