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Subject[PATCH v3] net: vmxnet3: fix possible NULL pointer dereference in vmxnet3_rq_cleanup()
Date
In vmxnet3_rq_create(), when dma_alloc_coherent() fails, 
vmxnet3_rq_destroy() is called. It sets rq->rx_ring[i].base to NULL. Then
vmxnet3_rq_create() returns an error to its callers mxnet3_rq_create_all()
-> vmxnet3_change_mtu(). Then vmxnet3_change_mtu() calls
vmxnet3_force_close() -> dev_close() in error handling code. And the driver
calls vmxnet3_close() -> vmxnet3_quiesce_dev() -> vmxnet3_rq_cleanup_all()
-> vmxnet3_rq_cleanup(). In vmxnet3_rq_cleanup(),
rq->rx_ring[ring_idx].base is accessed, but this variable is NULL, causing
a NULL pointer dereference.

To fix this possible bug, an if statement is added to check whether
rq->rx_ring[0].base is NULL in vmxnet3_rq_cleanup() and exit early if so.

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

[ 65.220135] BUG: kernel NULL pointer dereference, address: 0000000000000008
...
[ 65.222633] RIP: 0010:vmxnet3_rq_cleanup_all+0x396/0x4e0 [vmxnet3]
...
[ 65.227977] Call Trace:
...
[ 65.228262] vmxnet3_quiesce_dev+0x80f/0x8a0 [vmxnet3]
[ 65.228580] vmxnet3_close+0x2c4/0x3f0 [vmxnet3]
[ 65.228866] __dev_close_many+0x288/0x350
[ 65.229607] dev_close_many+0xa4/0x480
[ 65.231124] dev_close+0x138/0x230
[ 65.231933] vmxnet3_force_close+0x1f0/0x240 [vmxnet3]
[ 65.232248] vmxnet3_change_mtu+0x75d/0x920 [vmxnet3]
...

Fixes: d1a890fa37f27 ("net: VMware virtual Ethernet NIC driver: vmxnet3")
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Zixuan Fu <r33s3n6@gmail.com>
---
v2:
* Move check to the front and exit early if rq->rx_ring[0].base is NULL.
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 | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/net/vmxnet3/vmxnet3_drv.c b/drivers/net/vmxnet3/vmxnet3_drv.c
index d9d90baac72a..6b8f3aaa313f 100644
--- a/drivers/net/vmxnet3/vmxnet3_drv.c
+++ b/drivers/net/vmxnet3/vmxnet3_drv.c
@@ -1666,6 +1666,10 @@ vmxnet3_rq_cleanup(struct vmxnet3_rx_queue *rq,
u32 i, ring_idx;
struct Vmxnet3_RxDesc *rxd;

+ /* ring has already been cleaned up */
+ if (!rq->rx_ring[0].base)
+ return;
+
for (ring_idx = 0; ring_idx < 2; ring_idx++) {
for (i = 0; i < rq->rx_ring[ring_idx].size; i++) {
#ifdef __BIG_ENDIAN_BITFIELD
--
2.25.1
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