lpfc: Fix possible use-after-free and double free in lpfc_mbx_cmpl_rdp_page_a2()

If the bf_get() call in lpfc_mbx_cmpl_rdp_page_a2() does succeeds, execution
continues normally and mp gets kfree()d.

If the subsequent call to lpfc_sli_issue_mbox() fails execution jumps to the
error label where lpfc_mbuf_free() is called with mp->virt and mp->phys as
function arguments. This is the use after free. Following the use after free mp
gets kfree()d again which is a double free.
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: James Smart <james.smart@avagotech.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

drivers/scsi/lpfc/lpfc_mbox.c

@@ -2284,7 +2284,7 @@ lpfc_mbx_cmpl_rdp_page_a2(struct lpfc_hba *phba, LPFC_MBOXQ_t *mbox)
 			(struct lpfc_rdp_context *)(mbox->context2);
 
 	if (bf_get(lpfc_mqe_status, &mbox->u.mqe))
-		goto error;
+		goto error_mbuf_free;
 
 	lpfc_sli_bemem_bcopy(mp->virt, &rdp_context->page_a2,
 				DMP_SFF_PAGE_A2_SIZE);
@@ -2299,13 +2299,14 @@ lpfc_mbx_cmpl_rdp_page_a2(struct lpfc_hba *phba, LPFC_MBOXQ_t *mbox)
 	mbox->mbox_cmpl = lpfc_mbx_cmpl_rdp_link_stat;
 	mbox->context2 = (struct lpfc_rdp_context *) rdp_context;
 	if (lpfc_sli_issue_mbox(phba, mbox, MBX_NOWAIT) == MBX_NOT_FINISHED)
-		goto error;
+		goto error_cmd_free;
 
 	return;
 
-error:
+error_mbuf_free:
 	lpfc_mbuf_free(phba, mp->virt, mp->phys);
 	kfree(mp);
+error_cmd_free:
 	lpfc_sli4_mbox_cmd_free(phba, mbox);
 	rdp_context->cmpl(phba, rdp_context, FAILURE);
 }