scsi: be2iscsi: Fix use-after-free during IP updates

This fixes a bug found by Lv Yunlong where, because beiscsi_exec_nemb_cmd()
frees memory for the be_dma_mem cmd(), we can access freed memory when
beiscsi_if_clr_ip()/beiscsi_if_set_ip()'s call to beiscsi_exec_nemb_cmd()
fails and we access the freed req. This fixes the issue by having the
caller free the cmd's memory.

Link: https://lore.kernel.org/r/20210701190840.175120-1-michael.christie@oracle.comReported-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/be2iscsi/be_mgmt.c

@@ -235,8 +235,7 @@ static int beiscsi_exec_nemb_cmd(struct beiscsi_hba *phba,
 	wrb = alloc_mcc_wrb(phba, &tag);
 	if (!wrb) {
 		mutex_unlock(&ctrl->mbox_lock);
-		rc = -ENOMEM;
-		goto free_cmd;
+		return -ENOMEM;
 	}
 
 	sge = nonembedded_sgl(wrb);
@@ -269,24 +268,6 @@ static int beiscsi_exec_nemb_cmd(struct beiscsi_hba *phba,
 	/* copy the response, if any */
 	if (resp_buf)
 		memcpy(resp_buf, nonemb_cmd->va, resp_buf_len);
-	/**
-	 * This is special case of NTWK_GET_IF_INFO where the size of
-	 * response is not known. beiscsi_if_get_info checks the return
-	 * value to free DMA buffer.
-	 */
-	if (rc == -EAGAIN)
-		return rc;
-
-	/**
-	 * If FW is busy that is driver timed out, DMA buffer is saved with
-	 * the tag, only when the cmd completes this buffer is freed.
-	 */
-	if (rc == -EBUSY)
-		return rc;
-
-free_cmd:
-	dma_free_coherent(&ctrl->pdev->dev, nonemb_cmd->size,
-			    nonemb_cmd->va, nonemb_cmd->dma);
 	return rc;
 }
 
@@ -309,6 +290,19 @@ static int beiscsi_prep_nemb_cmd(struct beiscsi_hba *phba,
 	return 0;
 }
 
+static void beiscsi_free_nemb_cmd(struct beiscsi_hba *phba,
+				  struct be_dma_mem *cmd, int rc)
+{
+	/*
+	 * If FW is busy the DMA buffer is saved with the tag. When the cmd
+	 * completes this buffer is freed.
+	 */
+	if (rc == -EBUSY)
+		return;
+
+	dma_free_coherent(&phba->ctrl.pdev->dev, cmd->size, cmd->va, cmd->dma);
+}
+
 static void __beiscsi_eq_delay_compl(struct beiscsi_hba *phba, unsigned int tag)
 {
 	struct be_dma_mem *tag_mem;
@@ -344,8 +338,16 @@ int beiscsi_modify_eq_delay(struct beiscsi_hba *phba,
 				cpu_to_le32(set_eqd[i].delay_multiplier);
 	}
 
-	return beiscsi_exec_nemb_cmd(phba, &nonemb_cmd,
-				     __beiscsi_eq_delay_compl, NULL, 0);
+	rc = beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, __beiscsi_eq_delay_compl,
+				   NULL, 0);
+	if (rc) {
+		/*
+		 * Only free on failure. Async cmds are handled like -EBUSY
+		 * where it's handled for us.
+		 */
+		beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
+	}
+	return rc;
 }
 
 /**
@@ -372,6 +374,7 @@ int beiscsi_get_initiator_name(struct beiscsi_hba *phba, char *name, bool cfg)
 		req->hdr.version = 1;
 	rc = beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL,
 				   &resp, sizeof(resp));
+	beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
 	if (rc) {
 		beiscsi_log(phba, KERN_ERR,
 			    BEISCSI_LOG_CONFIG | BEISCSI_LOG_MBOX,
@@ -449,7 +452,9 @@ static int beiscsi_if_mod_gw(struct beiscsi_hba *phba,
 	req->ip_addr.ip_type = ip_type;
 	memcpy(req->ip_addr.addr, gw,
 	       (ip_type < BEISCSI_IP_TYPE_V6) ? IP_V4_LEN : IP_V6_LEN);
-	return beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL, NULL, 0);
+	rt_val = beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL, NULL, 0);
+	beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rt_val);
+	return rt_val;
 }
 
 int beiscsi_if_set_gw(struct beiscsi_hba *phba, u32 ip_type, u8 *gw)
@@ -499,8 +504,10 @@ int beiscsi_if_get_gw(struct beiscsi_hba *phba, u32 ip_type,
 	req = nonemb_cmd.va;
 	req->ip_type = ip_type;
 
-	return beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL,
-				     resp, sizeof(*resp));
+	rc = beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL, resp,
+				   sizeof(*resp));
+	beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
+	return rc;
 }
 
 static int
@@ -537,6 +544,7 @@ beiscsi_if_clr_ip(struct beiscsi_hba *phba,
 			    "BG_%d : failed to clear IP: rc %d status %d\n",
 			    rc, req->ip_params.ip_record.status);
 	}
+	beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
 	return rc;
 }
 
@@ -581,6 +589,7 @@ beiscsi_if_set_ip(struct beiscsi_hba *phba, u8 *ip,
 		if (req->ip_params.ip_record.status)
 			rc = -EINVAL;
 	}
+	beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
 	return rc;
 }
 
@@ -608,6 +617,7 @@ int beiscsi_if_en_static(struct beiscsi_hba *phba, u32 ip_type,
 		reldhcp->interface_hndl = phba->interface_handle;
 		reldhcp->ip_type = ip_type;
 		rc = beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL, NULL, 0);
+		beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
 		if (rc < 0) {
 			beiscsi_log(phba, KERN_WARNING, BEISCSI_LOG_CONFIG,
 				    "BG_%d : failed to release existing DHCP: %d\n",
@@ -689,7 +699,7 @@ int beiscsi_if_en_dhcp(struct beiscsi_hba *phba, u32 ip_type)
 	dhcpreq->interface_hndl = phba->interface_handle;
 	dhcpreq->ip_type = ip_type;
 	rc = beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL, NULL, 0);
-
+	beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
 exit:
 	kfree(if_info);
 	return rc;
@@ -762,11 +772,8 @@ int beiscsi_if_get_info(struct beiscsi_hba *phba, int ip_type,
 				    BEISCSI_LOG_INIT | BEISCSI_LOG_CONFIG,
 				    "BG_%d : Memory Allocation Failure\n");
 
-				/* Free the DMA memory for the IOCTL issuing */
-				dma_free_coherent(&phba->ctrl.pdev->dev,
-						    nonemb_cmd.size,
-						    nonemb_cmd.va,
-						    nonemb_cmd.dma);
+				beiscsi_free_nemb_cmd(phba, &nonemb_cmd,
+						      -ENOMEM);
 				return -ENOMEM;
 		}
 
@@ -781,15 +788,13 @@ int beiscsi_if_get_info(struct beiscsi_hba *phba, int ip_type,
 				      nonemb_cmd.va)->actual_resp_len;
 			ioctl_size += sizeof(struct be_cmd_req_hdr);
 
-			/* Free the previous allocated DMA memory */
-			dma_free_coherent(&phba->ctrl.pdev->dev, nonemb_cmd.size,
-					    nonemb_cmd.va,
-					    nonemb_cmd.dma);
-
+			beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
 			/* Free the virtual memory */
 			kfree(*if_info);
-		} else
+		} else {
+			beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
 			break;
+		}
 	} while (true);
 	return rc;
 }
@@ -806,8 +811,9 @@ int mgmt_get_nic_conf(struct beiscsi_hba *phba,
 	if (rc)
 		return rc;
 
-	return beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL,
-				     nic, sizeof(*nic));
+	rc = beiscsi_exec_nemb_cmd(phba, &nonemb_cmd, NULL, nic, sizeof(*nic));
+	beiscsi_free_nemb_cmd(phba, &nonemb_cmd, rc);
+	return rc;
 }
 
 static void beiscsi_boot_process_compl(struct beiscsi_hba *phba,