bnx2fc: fix memory leak and potential NULL pointer dereference.

If bnx2fc_allocate_hash_table() for some reasons fails, it is possible that the
hash_tbl_segments or the hash_tbl_pbl pointers are NULL.
In this case bnx2fc_free_hash_table() will panic the system.

this patch also fixes a memory leak, the hash_tbl_segments pointer was never
freed.
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Acked-by: Eddie Wai <eddie.wai@broadcom.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/bnx2fc/bnx2fc_hwi.c

@@ -1968,9 +1968,11 @@ static void bnx2fc_free_hash_table(struct bnx2fc_hba *hba)
 	int segment_count;
 	u32 *pbl;
 
-	segment_count = hba->hash_tbl_segment_count;
+	if (hba->hash_tbl_segments) {
 
 		pbl = hba->hash_tbl_pbl;
+		if (pbl) {
+			segment_count = hba->hash_tbl_segment_count;
 			for (i = 0; i < segment_count; ++i) {
 				dma_addr_t dma_address;
 
@@ -1982,7 +1984,11 @@ static void bnx2fc_free_hash_table(struct bnx2fc_hba *hba)
 						  BNX2FC_HASH_TBL_CHUNK_SIZE,
 						  hba->hash_tbl_segments[i],
 						  dma_address);
+			}
+		}
 
+		kfree(hba->hash_tbl_segments);
+		hba->hash_tbl_segments = NULL;
 	}
 
 	if (hba->hash_tbl_pbl) {