On Mon, 8 Aug 2022 16:10:50 +0800 Lin Ma wrote:
> 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]
>
> In short, there are data races between read and write of
> adapter->vfs_allocated_count. To fix this, we can add a new lock to
> protect members in adapter object. However, we cau use the existing
> rtnl_lock just as other drivers do. (See how dpaa2_eth_disconnect_mac is
> protected in dpaa2_eth_remove function). This patch adopts similar
> fixes.
>
> Fixes: c23d92b80e0b ("igb: Teardown SR-IOV before unregister_netdev()")
> Signed-off-by: Lin Ma <linma@xxxxxxxxxx>
> ---
> drivers/net/ethernet/intel/igb/igb_main.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> index d8b836a85cc3..e86ea4de05f8 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -3814,7 +3814,9 @@ static void igb_remove(struct pci_dev *pdev)
> igb_release_hw_control(adapter);
>
> #ifdef CONFIG_PCI_IOV
> + rtnl_lock();
> igb_disable_sriov(pdev);
> + rtnl_unlock();
> #endif
>
> unregister_netdev(netdev);
What about the disable path coming from sysfs? This looks incomplete to
me. Perhaps take a look at commit 1e53834ce541 ("ixgbe: Add locking to
prevent panic when setting sriov_numvfs to zero") for some inspiration.
