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Subject[PATCH v3] net: vmxnet3: fix possible use-after-free bugs in vmxnet3_rq_alloc_rx_buf()
Date
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>
---
v2:
* Free and clear pointers right after freeing them.
Thank Jakub Kicinski for helpful advice.
---
v3:
* Change targeting tree and add Fixes tag.
Thank Paolo Abeni for helpful advice.
---
drivers/net/vmxnet3/vmxnet3_drv.c | 2 ++
1 file changed, 2 insertions(+)

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
@@ -589,6 +589,7 @@ vmxnet3_rq_alloc_rx_buf(struct vmxnet3_rx_queue *rq, u32 ring_idx,
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;
}
@@ -613,6 +614,7 @@ vmxnet3_rq_alloc_rx_buf(struct vmxnet3_rx_queue *rq, u32 ring_idx,
if (dma_mapping_error(&adapter->pdev->dev,
rbi->dma_addr)) {
put_page(rbi->page);
+ rbi->page = NULL;
rq->stats.rx_buf_alloc_failure++;
break;
}
--
2.25.1
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