[PATCH 5.4 345/389] igb: Add lock to avoid data race

Greg Kroah-Hartman
2022-08-23T11:56:58Z

From: Lin Ma <linma@zju.edu.cn>

commit 6faee3d4ee8be0f0367d0c3d826afb3571b7a5e0 upstream.

The commit c23d92b80e0b ("igb: Teardown SR-IOV before
unregister_netdev()") places the unregister_netdev() call after the
igb_disable_sriov() call to avoid functionality issue.

However, it introduces several race conditions when detaching a device.
For example, when .remove() is called, the below interleaving leads to
use-after-free.

(FREE from device detaching) | (USE from netdev core)
igb_remove | igb_ndo_get_vf_config
igb_disable_sriov | vf >= adapter->vfs_allocated_count?
kfree(adapter->vf_data) |
adapter->vfs_allocated_count = 0 |
| memcpy(... adapter->vf_data[vf]

Moreover, the igb_disable_sriov() also suffers from data race with the
requests from VF driver.

(FREE from device detaching) | (USE from requests)
igb_remove | igb_msix_other
igb_disable_sriov | igb_msg_task
kfree(adapter->vf_data) | vf < adapter->vfs_allocated_count
adapter->vfs_allocated_count = 0 |

To this end, this commit first eliminates the data races from netdev
core by using rtnl_lock (similar to commit 719479230893 ("dpaa2-eth: add
MAC/PHY support through phylink")). And then adds a spinlock to
eliminate races from driver requests. (similar to commit 1e53834ce541
("ixgbe: Add locking to prevent panic when setting sriov_numvfs to zero")

Fixes: c23d92b80e0b ("igb: Teardown SR-IOV before unregister_netdev()")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://lore.kernel.org/r/20220817184921.735244-1-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/intel/igb/igb.h | 2 ++
drivers/net/ethernet/intel/igb/igb_main.c | 12 +++++++++++-
2 files changed, 13 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/intel/igb/igb.h
+++ b/drivers/net/ethernet/intel/igb/igb.h
@@ -594,6 +594,8 @@ struct igb_adapter {
struct igb_mac_addr *mac_table;
struct vf_mac_filter vf_macs;
struct vf_mac_filter *vf_mac_list;
+ /* lock for VF resources */
+ spinlock_t vfs_lock;
};

/* flags controlling PTP/1588 function */
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -3491,6 +3491,7 @@ static int igb_disable_sriov(struct pci_
struct net_device *netdev = pci_get_drvdata(pdev);
struct igb_adapter *adapter = netdev_priv(netdev);
struct e1000_hw *hw = &adapter->hw;
+ unsigned long flags;

/* reclaim resources allocated to VFs */
if (adapter->vf_data) {
@@ -3503,12 +3504,13 @@ static int igb_disable_sriov(struct pci_
pci_disable_sriov(pdev);
msleep(500);
}
-
+ spin_lock_irqsave(&adapter->vfs_lock, flags);
kfree(adapter->vf_mac_list);
adapter->vf_mac_list = NULL;
kfree(adapter->vf_data);
adapter->vf_data = NULL;
adapter->vfs_allocated_count = 0;
+ spin_unlock_irqrestore(&adapter->vfs_lock, flags);
wr32(E1000_IOVCTL, E1000_IOVCTL_REUSE_VFQ);
wrfl();
msleep(100);
@@ -3668,7 +3670,9 @@ static void igb_remove(struct pci_dev *p
igb_release_hw_control(adapter);

#ifdef CONFIG_PCI_IOV
+ rtnl_lock();
igb_disable_sriov(pdev);
+ rtnl_unlock();
#endif

unregister_netdev(netdev);
@@ -3829,6 +3833,9 @@ static int igb_sw_init(struct igb_adapte

spin_lock_init(&adapter->nfc_lock);
spin_lock_init(&adapter->stats64_lock);
+
+ /* init spinlock to avoid concurrency of VF resources */
+ spin_lock_init(&adapter->vfs_lock);
#ifdef CONFIG_PCI_IOV
switch (hw->mac.type) {
case e1000_82576:
@@ -7569,8 +7576,10 @@ unlock:
static void igb_msg_task(struct igb_adapter *adapter)
{
struct e1000_hw *hw = &adapter->hw;
+ unsigned long flags;
u32 vf;

+ spin_lock_irqsave(&adapter->vfs_lock, flags);
for (vf = 0; vf < adapter->vfs_allocated_count; vf++) {
/* process any reset requests */
if (!igb_check_for_rst(hw, vf))
@@ -7584,6 +7593,7 @@ static void igb_msg_task(struct igb_adap
if (!igb_check_for_ack(hw, vf))
igb_rcv_ack_from_vf(adapter, vf);
}
+ spin_unlock_irqrestore(&adapter->vfs_lock, flags);
}

/**