CVE-2023-4387: Use After Free (CWE-416)
value: A use-after-free flaw was found in vmxnet3_rq_alloc_rx_buf in drivers/net/vmxnet3/vmxnet3_drv.c in VMware's vmxnet3 ethernet NIC driver in the Linux Kernel. This issue could allow a local attacker to crash the system due to a double-free while cleaning up vmxnet3_rq_cleanup_all, which could also lead to a kernel information leak problem.
CWE description: The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
CVSS v3 base score: 7.1
Published: 2023-08-16T19:15Z
Repository: https://github.com/torvalds/linux
Language: C
Files changed: drivers/net/vmxnet3/vmxnet3_drv.c
Commit date: 2022-05-17 12:02:27 +0200
Commit message: net: vmxnet3: fix possible use-after-free bugs in vmxnet3_rq_alloc_rx_buf()

In vmxnet3_rq_alloc_rx_buf(), when dma_map_single() fails, rbi->skb is
freed immediately. Similarly, in another branch, when dma_map_page() fails,
rbi->page is also freed. In the two cases, vmxnet3_rq_alloc_rx_buf()
returns an error to its callers vmxnet3_rq_init() -> vmxnet3_rq_init_all()
-> vmxnet3_activate_dev(). Then vmxnet3_activate_dev() calls
vmxnet3_rq_cleanup_all() in error handling code, and rbi->skb or rbi->page
are freed again in vmxnet3_rq_cleanup_all(), causing use-after-free bugs.

To fix these possible bugs, rbi->skb and rbi->page should be cleared after
they are freed.

The error log in our fault-injection testing is shown as follows:

[   14.319016] BUG: KASAN: use-after-free in consume_skb+0x2f/0x150
...
[   14.321586] Call Trace:
...
[   14.325357]  consume_skb+0x2f/0x150
[   14.325671]  vmxnet3_rq_cleanup_all+0x33a/0x4e0 [vmxnet3]
[   14.326150]  vmxnet3_activate_dev+0xb9d/0x2ca0 [vmxnet3]
[   14.326616]  vmxnet3_open+0x387/0x470 [vmxnet3]
...
[   14.361675] Allocated by task 351:
...
[   14.362688]  __netdev_alloc_skb+0x1b3/0x6f0
[   14.362960]  vmxnet3_rq_alloc_rx_buf+0x1b0/0x8d0 [vmxnet3]
[   14.363317]  vmxnet3_activate_dev+0x3e3/0x2ca0 [vmxnet3]
[   14.363661]  vmxnet3_open+0x387/0x470 [vmxnet3]
...
[   14.367309]
[   14.367412] Freed by task 351:
...
[   14.368932]  __dev_kfree_skb_any+0xd2/0xe0
[   14.369193]  vmxnet3_rq_alloc_rx_buf+0x71e/0x8d0 [vmxnet3]
[   14.369544]  vmxnet3_activate_dev+0x3e3/0x2ca0 [vmxnet3]
[   14.369883]  vmxnet3_open+0x387/0x470 [vmxnet3]
[   14.370174]  __dev_open+0x28a/0x420
[   14.370399]  __dev_change_flags+0x192/0x590
[   14.370667]  dev_change_flags+0x7a/0x180
[   14.370919]  do_setlink+0xb28/0x3570
[   14.371150]  rtnl_newlink+0x1160/0x1740
[   14.371399]  rtnetlink_rcv_msg+0x5bf/0xa50
[   14.371661]  netlink_rcv_skb+0x1cd/0x3e0
[   14.371913]  netlink_unicast+0x5dc/0x840
[   14.372169]  netlink_sendmsg+0x856/0xc40
[   14.372420]  ____sys_sendmsg+0x8a7/0x8d0
[   14.372673]  __sys_sendmsg+0x1c2/0x270
[   14.372914]  do_syscall_64+0x41/0x90
[   14.373145]  entry_SYSCALL_64_after_hwframe+0x44/0xae
...

Fixes: 5738a09d58d5a ("vmxnet3: fix checks for dma mapping errors")
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Zixuan Fu <r33s3n6@gmail.com>
Link: https://lore.kernel.org/r/20220514050656.2636588-1-r33s3n6@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Diff: diff --git a/drivers/net/vmxnet3/vmxnet3_drv.c b/drivers/net/vmxnet3/vmxnet3_drv.c
index d9d90baac72a..1154f1884212 100644
--- a/drivers/net/vmxnet3/vmxnet3_drv.c
+++ b/drivers/net/vmxnet3/vmxnet3_drv.c
@@ -587,10 +587,11 @@ vmxnet3_rq_alloc_rx_buf(struct vmxnet3_rx_queue *rq, u32 ring_idx,
 						rbi->skb->data, rbi->len,
 						DMA_FROM_DEVICE);
 				if (dma_mapping_error(&adapter->pdev->dev,
 						      rbi->dma_addr)) {
 					dev_kfree_skb_any(rbi->skb);
+					rbi->skb = NULL;
 					rq->stats.rx_buf_alloc_failure++;
 					break;
 				}
 			} else {
 				/* rx buffer skipped by the device */
@@ -611,10 +612,11 @@ vmxnet3_rq_alloc_rx_buf(struct vmxnet3_rx_queue *rq, u32 ring_idx,
 						rbi->page, 0, PAGE_SIZE,
 						DMA_FROM_DEVICE);
 				if (dma_mapping_error(&adapter->pdev->dev,
 						      rbi->dma_addr)) {
 					put_page(rbi->page);
+					rbi->page = NULL;
 					rq->stats.rx_buf_alloc_failure++;
 					break;
 				}
 			} else {
 				/* rx buffers skipped by the device */

Fixed code: 					rbi->skb = NULL;
					rbi->page = NULL;