[v4,1/3] vhost: fix error path when setting memory tables

  If an error is encountered before the memory regions are
parsed, the file descriptors for these shared buffers are
leaked.

This patch fixes this by closing the message file descriptors
on error, taking care of avoiding double closing of the file
descriptors. guest_pages is also freed, even though it was not
leaked as its pointer was not overridden on subsequent function
calls.

Fixes: 8f972312b8f4 ("vhost: support vhost-user")
Cc: stable@dpdk.org

Reported-by: Xuan Ding <xuan.ding@intel.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>
---
 lib/librte_vhost/vhost_user.c | 60 ++++++++++++++++++++++-------------
 1 file changed, 38 insertions(+), 22 deletions(-)
  

>-----Original Message-----
>From: Maxime Coquelin <maxime.coquelin@redhat.com>
>Sent: Friday, November 13, 2020 1:10 AM
>To: dev@dpdk.org; xuan.ding@intel.com; stephen@networkplumber.org;
>NBU-Contact-Thomas Monjalon <thomas@monjalon.net>; stable@dpdk.org;
>chenbo.xia@intel.com; Xueming(Steven) Li <xuemingl@nvidia.com>
>Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
>Subject: [PATCH v4 1/3] vhost: fix error path when setting memory tables
>
>If an error is encountered before the memory regions are parsed, the file
>descriptors for these shared buffers are leaked.
>
>This patch fixes this by closing the message file descriptors on error, taking
>care of avoiding double closing of the file descriptors. guest_pages is also
>freed, even though it was not leaked as its pointer was not overridden on
>subsequent function calls.
>
>Fixes: 8f972312b8f4 ("vhost: support vhost-user")
>Cc: stable@dpdk.org
>
>Reported-by: Xuan Ding <xuan.ding@intel.com>
>Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>
>---
> lib/librte_vhost/vhost_user.c | 60 ++++++++++++++++++++++-------------
> 1 file changed, 38 insertions(+), 22 deletions(-)
>
>diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c index
>8a8726f8b8..3898c93d1f 100644
>--- a/lib/librte_vhost/vhost_user.c
>+++ b/lib/librte_vhost/vhost_user.c
>@@ -99,8 +99,15 @@ close_msg_fds(struct VhostUserMsg *msg)  {
> 	int i;
>
>-	for (i = 0; i < msg->fd_num; i++)
>-		close(msg->fds[i]);
>+	for (i = 0; i < msg->fd_num; i++) {
>+		int fd = msg->fds[i];
>+
>+		if (fd == -1)
>+			continue;
>+
>+		msg->fds[i] = -1;
>+		close(fd);
>+	}
> }
>
> /*
>@@ -1004,7 +1011,6 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 	uint64_t alignment;
> 	uint32_t i;
> 	int populate;
>-	int fd;
>
> 	if (validate_msg_fds(msg, memory->nregions) != 0)
> 		return RTE_VHOST_MSG_RESULT_ERR;
>@@ -1012,7 +1018,7 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 	if (memory->nregions > VHOST_MEMORY_MAX_NREGIONS) {
> 		VHOST_LOG_CONFIG(ERR,
> 			"too many memory regions (%u)\n", memory-
>>nregions);
>-		return RTE_VHOST_MSG_RESULT_ERR;
>+		goto close_msg_fds;
> 	}
>
> 	if (dev->mem && !vhost_memory_changed(memory, dev->mem))
>{ @@ -1054,7 +1060,7 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 				"(%d) failed to allocate memory "
> 				"for dev->guest_pages\n",
> 				dev->vid);
>-			return RTE_VHOST_MSG_RESULT_ERR;
>+			goto close_msg_fds;
> 		}
> 	}
>
>@@ -1064,18 +1070,23 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 		VHOST_LOG_CONFIG(ERR,
> 			"(%d) failed to allocate memory for dev->mem\n",
> 			dev->vid);
>-		return RTE_VHOST_MSG_RESULT_ERR;
>+		goto free_guest_pages;
> 	}
> 	dev->mem->nregions = memory->nregions;
>
> 	for (i = 0; i < memory->nregions; i++) {
>-		fd  = msg->fds[i];
> 		reg = &dev->mem->regions[i];
>
> 		reg->guest_phys_addr = memory->regions[i].guest_phys_addr;
> 		reg->guest_user_addr = memory->regions[i].userspace_addr;
> 		reg->size            = memory->regions[i].memory_size;
>-		reg->fd              = fd;
>+		reg->fd              = msg->fds[i];
>+
>+		/*
>+		 * Assign invalid file descriptor value to avoid double
>+		 * closing on error path.
>+		 */
>+		msg->fds[i] = -1;
>
> 		mmap_offset = memory->regions[i].mmap_offset;
>
>@@ -1085,7 +1096,7 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 				"mmap_offset (%#"PRIx64") and memory_size
>"
> 				"(%#"PRIx64") overflow\n",
> 				mmap_offset, reg->size);
>-			goto err_mmap;
>+			goto free_mem_table;
> 		}
>
> 		mmap_size = reg->size + mmap_offset;
>@@ -1098,11 +1109,11 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 		 * to avoid failure, make sure in caller to keep length
> 		 * aligned.
> 		 */
>-		alignment = get_blk_size(fd);
>+		alignment = get_blk_size(reg->fd);
> 		if (alignment == (uint64_t)-1) {
> 			VHOST_LOG_CONFIG(ERR,
> 				"couldn't get hugepage size through fstat\n");
>-			goto err_mmap;
>+			goto free_mem_table;
> 		}
> 		mmap_size = RTE_ALIGN_CEIL(mmap_size, alignment);
> 		if (mmap_size == 0) {
>@@ -1118,17 +1129,17 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 			VHOST_LOG_CONFIG(ERR, "mmap size (0x%" PRIx64 ")
>"
> 					"or alignment (0x%" PRIx64 ") is
>invalid\n",
> 					reg->size + mmap_offset, alignment);
>-			goto err_mmap;
>+			goto free_mem_table;
> 		}
>
> 		populate = dev->async_copy ? MAP_POPULATE : 0;
> 		mmap_addr = mmap(NULL, mmap_size, PROT_READ |
>PROT_WRITE,
>-				 MAP_SHARED | populate, fd, 0);
>+				 MAP_SHARED | populate, reg->fd, 0);
>
> 		if (mmap_addr == MAP_FAILED) {
> 			VHOST_LOG_CONFIG(ERR,
> 				"mmap region %u failed.\n", i);
>-			goto err_mmap;
>+			goto free_mem_table;
> 		}
>
> 		reg->mmap_addr = mmap_addr;
>@@ -1141,7 +1152,7 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 				VHOST_LOG_CONFIG(ERR,
> 					"adding guest pages to region %u
>failed.\n",
> 					i);
>-				goto err_mmap;
>+				goto free_mem_table;
> 			}
>
> 		VHOST_LOG_CONFIG(INFO,
>@@ -1184,17 +1195,17 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 		if (read_vhost_message(main_fd, &ack_msg) <= 0) {
> 			VHOST_LOG_CONFIG(ERR,
> 				"Failed to read qemu ack on postcopy set-
>mem-table\n");
>-			goto err_mmap;
>+			goto free_mem_table;
> 		}
>
> 		if (validate_msg_fds(&ack_msg, 0) != 0)
>-			goto err_mmap;
>+			goto free_mem_table;
>
> 		if (ack_msg.request.master != VHOST_USER_SET_MEM_TABLE)
>{
> 			VHOST_LOG_CONFIG(ERR,
> 				"Bad qemu ack on postcopy set-mem-table
>(%d)\n",
> 				ack_msg.request.master);
>-			goto err_mmap;
>+			goto free_mem_table;
> 		}
>
> 		/* Now userfault register and we can use the memory */ @@
>-1218,7 +1229,7 @@ vhost_user_set_mem_table(struct virtio_net **pdev,
>struct VhostUserMsg *msg,
> 					"Failed to register ufd for region %d:
>(ufd = %d) %s\n",
> 					i, dev->postcopy_ufd,
> 					strerror(errno));
>-				goto err_mmap;
>+				goto free_mem_table;
> 			}
> 			VHOST_LOG_CONFIG(INFO,
> 				"\t userfaultfd registered for range : "
>@@ -1227,7 +1238,7 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 				(uint64_t)reg_struct.range.start +
> 				(uint64_t)reg_struct.range.len - 1);  #else
>-			goto err_mmap;
>+			goto free_mem_table;
> #endif
> 		}
> 	}
>@@ -1249,7 +1260,7 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
> 			dev = translate_ring_addresses(dev, i);
> 			if (!dev) {
> 				dev = *pdev;
>-				goto err_mmap;
>+				goto free_mem_table;
> 			}
>
> 			*pdev = dev;
>@@ -1260,10 +1271,15 @@ vhost_user_set_mem_table(struct virtio_net
>**pdev, struct VhostUserMsg *msg,
>
> 	return RTE_VHOST_MSG_RESULT_OK;
>
>-err_mmap:
>+free_mem_table:
> 	free_mem_region(dev);
> 	rte_free(dev->mem);
> 	dev->mem = NULL;
>+free_guest_pages:
>+	rte_free(dev->guest_pages);
>+	dev->guest_pages = NULL;
>+close_msg_fds:
>+	close_msg_fds(msg);
> 	return RTE_VHOST_MSG_RESULT_ERR;
> }
>
>--
>2.26.2

Reviewed-by: Xueming(Steven) Li <xuemingl@nvidia.com>