On Thu, Apr 21, 2022 at 05:42:36PM +0800, Zixuan Fu wrote:
> In xhci_create_rhub_port_array(), when rhub->num_ports is zero,
> rhub->ports would not be set; when kcalloc_node() fails, rhub->ports
> would be set to NULL. In these two cases, xhci_create_rhub_port_array()
> just returns void, and thus its callers are unaware of the error.
>
> Then rhub->ports is dereferenced in xhci_usb3_hub_descriptor() or
> xhci_usb2_hub_descriptor().
>
> To fix the bug, xhci_setup_port_arrays() should return an integer to
> indicate a possible error, and its callers should handle the error.
>
> Here is the log when this bug occurred in our fault-injection testing:
>
> [ 24.001309] BUG: kernel NULL pointer dereference, address: 0000000000000000
> ...
> [ 24.003992] RIP: 0010:xhci_hub_control+0x3f5/0x60d0 [xhci_hcd]
> ...
> [ 24.009803] Call Trace:
> [ 24.010014] <TASK>
> [ 24.011310] usb_hcd_submit_urb+0x1233/0x1fd0
> [ 24.017071] usb_start_wait_urb+0x115/0x310
> [ 24.017641] usb_control_msg+0x28a/0x450
> [ 24.019046] hub_probe+0xb16/0x2320
> [ 24.019757] usb_probe_interface+0x4f1/0x930
> [ 24.019765] really_probe+0x33d/0x970
> [ 24.019768] __driver_probe_device+0x157/0x210
> [ 24.019772] driver_probe_device+0x4f/0x340
> [ 24.019775] __device_attach_driver+0x2ee/0x3a0
> ...
>
> Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>
> Signed-off-by: Zixuan Fu <r33s3n6@xxxxxxxxx>
> ---
> drivers/usb/host/xhci-mem.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> index bbb27ee2c6a3..024515346c39 100644
> --- a/drivers/usb/host/xhci-mem.c
> +++ b/drivers/usb/host/xhci-mem.c
> @@ -2235,7 +2235,7 @@ static void xhci_add_in_port(struct xhci_hcd *xhci, unsigned int num_ports,
> /* FIXME: Should we disable ports not in the Extended Capabilities? */
> }
>
> -static void xhci_create_rhub_port_array(struct xhci_hcd *xhci,
> +static int xhci_create_rhub_port_array(struct xhci_hcd *xhci,
> struct xhci_hub *rhub, gfp_t flags)
> {
> int port_index = 0;
> @@ -2243,11 +2243,11 @@ static void xhci_create_rhub_port_array(struct xhci_hcd *xhci,
> struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
>
> if (!rhub->num_ports)
> - return;
> + return -EINVAL;
> rhub->ports = kcalloc_node(rhub->num_ports, sizeof(*rhub->ports),
> flags, dev_to_node(dev));
> if (!rhub->ports)
> - return;
> + return -ENOMEM;
>
> for (i = 0; i < HCS_MAX_PORTS(xhci->hcs_params1); i++) {
> if (xhci->hw_ports[i].rhub != rhub ||
> @@ -2259,6 +2259,7 @@ static void xhci_create_rhub_port_array(struct xhci_hcd *xhci,
> if (port_index == rhub->num_ports)
> break;
> }
> + return 0;
> }
>
> /*
> @@ -2277,6 +2278,7 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags)
> int cap_count = 0;
> u32 cap_start;
> struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
> + int ret;
>
> num_ports = HCS_MAX_PORTS(xhci->hcs_params1);
> xhci->hw_ports = kcalloc_node(num_ports, sizeof(*xhci->hw_ports),
> @@ -2367,8 +2369,13 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags)
> * Not sure how the USB core will handle a hub with no ports...
> */
>
> - xhci_create_rhub_port_array(xhci, &xhci->usb2_rhub, flags);
> - xhci_create_rhub_port_array(xhci, &xhci->usb3_rhub, flags);
> + ret = xhci_create_rhub_port_array(xhci, &xhci->usb2_rhub, flags);
> + if (ret)
> + return ret;
> +
> + ret = xhci_create_rhub_port_array(xhci, &xhci->usb3_rhub, flags);
> + if (ret)
> + return ret;
What about the memory allocated by the first call to
xhci_create_rhub_port_array()? Is that now lost? Same for everything
else allocated before these calls, how is that cleaned up properly?
thanks,
greg k-h
