igbvf: Fix leak in TX DMA error cleanup

If an error is encountered while mapping TX buffers, the driver should unmap any buffers already mapped for that skb.

Because count is incremented before each frag mapping, it will always match the correct number of unmappings needed when dma_error is reached. Decrementing count before the while loop in dma_error causes an off-by-one error. If any mapping was successful before an unsuccessful mapping, exactly one DMA mapping (the head) would leak.

This bug was introduced by a 2010 fix for an endless loop in dma_error. All other affected drivers have already been fixed.

---
 drivers/net/ethernet/intel/igbvf/netdev.c | 2 --
 1 file changed, 2 deletions(-)

index ac57212ab02bd..19b2228e80bae 100644
@@ -2190,8 +2190,6 @@ static inline int igbvf_tx_map_adv(struct igbvf_adapter *adapter,
 	buffer_info->time_stamp = 0;
 	buffer_info->length = 0;
 	buffer_info->mapped_as_page = false;
-	if (count)
-		count--;
 
 	/* clear timestamp and dma mappings for remaining portion of packet */
 	while (count--) {

2.43.0