vhost/scsi: Fix incorrect early vhost_scsi_handle_vq failures

This patch fixes vhost_scsi_handle_vq() failure cases that result in BUG_ON()
getting triggered when vhost_scsi_free_cmd() is called, and ->tvc_se_cmd has
not been initialized by target_submit_cmd_map_sgls().

It changes tcm_vhost_release_cmd() to use tcm_vhost_cmd->tvc_nexus for obtaining
se_session pointer reference.  Also, avoid calling put_page() on NULL sg->page
entries in vhost_scsi_map_to_sgl() failure path.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 29 insertions, 23 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 29dfdf66bbc5..62de820ae2f4 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -462,7 +462,7 @@ static void tcm_vhost_release_cmd(struct se_cmd *se_cmd)
 {
         struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
                                 struct tcm_vhost_cmd, tvc_se_cmd);
-        struct se_session *se_sess = se_cmd->se_sess;
+        struct se_session *se_sess = tv_cmd->tvc_nexus->tvn_se_sess;
         int i;
 
         if (tv_cmd->tvc_sgl_count) {
@@ -864,9 +864,11 @@ vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *cmd,
                 ret = vhost_scsi_map_to_sgl(cmd, sg, sgl_count, &iov[i],
                                             cmd->tvc_upages, write);
                 if (ret < 0) {
-                        for (i = 0; i < cmd->tvc_sgl_count; i++)
-                                put_page(sg_page(&cmd->tvc_sgl[i]));
-
+                        for (i = 0; i < cmd->tvc_sgl_count; i++) {
+                                struct page *page = sg_page(&cmd->tvc_sgl[i]);
+                                if (page)
+                                        put_page(page);
+                        }
                         cmd->tvc_sgl_count = 0;
                         return ret;
                 }
@@ -905,9 +907,11 @@ vhost_scsi_map_iov_to_prot(struct tcm_vhost_cmd *cmd,
                 ret = vhost_scsi_map_to_sgl(cmd, prot_sg, prot_sgl_count, &iov[i],
                                             cmd->tvc_upages, write);
                 if (ret < 0) {
-                        for (i = 0; i < cmd->tvc_prot_sgl_count; i++)
-                                put_page(sg_page(&cmd->tvc_prot_sgl[i]));
-
+                        for (i = 0; i < cmd->tvc_prot_sgl_count; i++) {
+                                struct page *page = sg_page(&cmd->tvc_prot_sgl[i]);
+                                if (page)
+                                        put_page(page);
+                        }
                         cmd->tvc_prot_sgl_count = 0;
                         return ret;
                 }
@@ -1065,12 +1069,14 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
                 if (unlikely(vq->iov[0].iov_len < req_size)) {
                         pr_err("Expecting virtio-scsi header: %zu, got %zu\n",
                                req_size, vq->iov[0].iov_len);
-                        break;
+                        vhost_scsi_send_bad_target(vs, vq, head, out);
+                        continue;
                 }
                 ret = memcpy_fromiovecend(req, &vq->iov[0], 0, req_size);
                 if (unlikely(ret)) {
                         vq_err(vq, "Faulted on virtio_scsi_cmd_req\n");
-                        break;
+                        vhost_scsi_send_bad_target(vs, vq, head, out);
+                        continue;
                 }
 
                 /* virtio-scsi spec requires byte 0 of the lun to be 1 */
@@ -1101,14 +1107,16 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
                                 if (data_direction != DMA_TO_DEVICE) {
                                         vq_err(vq, "Received non zero do_pi_niov"
                                                 ", but wrong data_direction\n");
-                                        goto err_cmd;
+                                        vhost_scsi_send_bad_target(vs, vq, head, out);
+                                        continue;
                                 }
                                 prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesout);
                         } else if (v_req_pi.pi_bytesin) {
                                 if (data_direction != DMA_FROM_DEVICE) {
                                         vq_err(vq, "Received non zero di_pi_niov"
                                                 ", but wrong data_direction\n");
-                                        goto err_cmd;
+                                        vhost_scsi_send_bad_target(vs, vq, head, out);
+                                        continue;
                                 }
                                 prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesin);
                         }
@@ -1148,7 +1156,8 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
                         vq_err(vq, "Received SCSI CDB with command_size: %d that"
                                 " exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
                                 scsi_command_size(cdb), TCM_VHOST_MAX_CDB_SIZE);
-                        goto err_cmd;
+                        vhost_scsi_send_bad_target(vs, vq, head, out);
+                        continue;
                 }
 
                 cmd = vhost_scsi_get_tag(vq, tpg, cdb, tag, lun, task_attr,
@@ -1157,7 +1166,8 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
                 if (IS_ERR(cmd)) {
                         vq_err(vq, "vhost_scsi_get_tag failed %ld\n",
                                         PTR_ERR(cmd));
-                        goto err_cmd;
+                        vhost_scsi_send_bad_target(vs, vq, head, out);
+                        continue;
                 }
 
                 pr_debug("Allocated tv_cmd: %p exp_data_len: %d, data_direction"
@@ -1178,7 +1188,9 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
                         if (unlikely(ret)) {
                                 vq_err(vq, "Failed to map iov to"
                                         " prot_sgl\n");
-                                goto err_free;
+                                tcm_vhost_release_cmd(&cmd->tvc_se_cmd);
+                                vhost_scsi_send_bad_target(vs, vq, head, out);
+                                continue;
                         }
                 }
                 if (data_direction != DMA_NONE) {
@@ -1187,7 +1199,9 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
                                         data_direction == DMA_FROM_DEVICE);
                         if (unlikely(ret)) {
                                 vq_err(vq, "Failed to map iov to sgl\n");
-                                goto err_free;
+                                tcm_vhost_release_cmd(&cmd->tvc_se_cmd);
+                                vhost_scsi_send_bad_target(vs, vq, head, out);
+                                continue;
                         }
                 }
                 /*
@@ -1205,14 +1219,6 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
                 INIT_WORK(&cmd->work, tcm_vhost_submission_work);
                 queue_work(tcm_vhost_workqueue, &cmd->work);
         }
-
-        mutex_unlock(&vq->mutex);
-        return;
-
-err_free:
-        vhost_scsi_free_cmd(cmd);
-err_cmd:
-        vhost_scsi_send_bad_target(vs, vq, head, out);
 out:
         mutex_unlock(&vq->mutex);
 }