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.
In the driver, xhci_create_rhub_port_array() is only used in
xhci_setup_port_arrays(), and only xhci_mem_init() calls
xhci_setup_port_arrays() and does all cleanup work when it fails.
Specifically, xhci_mem_init() calls xhci_mem_cleanup(), which eventually
calls kfree(xhci->usb2_rhub.ports) and kfree(xhci->usb3_rhub.ports). For
this reason, when xhci_create_rhub_port_array() fails,
xhci_setup_port_arrays() should return the error code directly, without
freeing the memory allocated in this function.
The error log in our fault-injection testing is shown as follows:
[ 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>
---
v2:
* Explain the reason why xhci_setup_port_arrays() returns without freeing the memory in error handling code.
Thank Greg KH for helpful advice.
---
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;
return 0;
}
--
2.25.1
