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usb: xhci: Fix slot_id resource race conflict 

xHC controller may immediately reuse a slot_id after it's disabled,
giving it to a new enumerating device before the xhci driver freed
all resources related to the disabled device.

In such a scenario, device-A with slot_id equal to 1 is disconnecting
while device-B is enumerating, device-B will fail to enumerate in the
follow sequence.

1.[device-A] send disable slot command
2.[device-B] send enable slot command
3.[device-A] disable slot command completed and wakeup waiting thread
4.[device-B] enable slot command completed with slot_id equal to 1 and
	     wakeup waiting thread
5.[device-B] driver checks that slot_id is still in use (by device-A) in
	     xhci_alloc_virt_device, and fail to enumerate due to this
	     conflict
6.[device-A] xhci->devs[slot_id] set to NULL in xhci_free_virt_device

To fix driver's slot_id resources conflict, clear xhci->devs[slot_id] and
xhci->dcbba->dev_context_ptrs[slot_id] pointers in the interrupt context
when disable slot command completes successfully. Simultaneously, adjust
function xhci_free_virt_device to accurately handle device release.

[minor smatch warning and commit message fix -Mathias]

Cc: stable@vger.kernel.org
Fixes: 7faac1953e ("xhci: avoid race between disable slot command and host runtime suspend")
Signed-off-by: Weitao Wang <WeitaoWang-oc@zhaoxin.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250819125844.2042452-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/1322/head
Weitao Wang 2025-08-19 15:58:43 +03:00 committed by Greg Kroah-Hartman
parent 309b6341d5
commit 2eb0337615
5 changed files with 35 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/usb/host/xhci-hub.c
View File

@ -704,8 +704,7 @@ static int xhci_enter_test_mode(struct xhci_hcd *xhci,
if (!xhci->devs[i])
continue;
retval = xhci_disable_slot(xhci, i);
xhci_free_virt_device(xhci, i);
retval = xhci_disable_and_free_slot(xhci, i);
if (retval)
xhci_err(xhci, "Failed to disable slot %d, %d. Enter test mode anyway\n",
i, retval);

22
drivers/usb/host/xhci-mem.c
View File

@ -865,21 +865,20 @@ free_tts:
* will be manipulated by the configure endpoint, allocate device, or update
* hub functions while this function is removing the TT entries from the list.
*/
void xhci_free_virt_device(struct xhci_hcd *xhci, int slot_id)
void xhci_free_virt_device(struct xhci_hcd *xhci, struct xhci_virt_device *dev,
int slot_id)
{
struct xhci_virt_device *dev;
int i;
int old_active_eps = 0;
/* Slot ID 0 is reserved */
if (slot_id == 0 || !xhci->devs[slot_id])
if (slot_id == 0 || !dev)
return;
dev = xhci->devs[slot_id];
xhci->dcbaa->dev_context_ptrs[slot_id] = 0;
if (!dev)
return;
/* If device ctx array still points to _this_ device, clear it */
if (dev->out_ctx &&
xhci->dcbaa->dev_context_ptrs[slot_id] == cpu_to_le64(dev->out_ctx->dma))
xhci->dcbaa->dev_context_ptrs[slot_id] = 0;
trace_xhci_free_virt_device(dev);
@ -920,8 +919,9 @@ void xhci_free_virt_device(struct xhci_hcd *xhci, int slot_id)
dev->udev->slot_id = 0;
if (dev->rhub_port && dev->rhub_port->slot_id == slot_id)
dev->rhub_port->slot_id = 0;
kfree(xhci->devs[slot_id]);
xhci->devs[slot_id] = NULL;
if (xhci->devs[slot_id] == dev)
xhci->devs[slot_id] = NULL;
kfree(dev);
}
/*
@ -962,7 +962,7 @@ static void xhci_free_virt_devices_depth_first(struct xhci_hcd *xhci, int slot_i
out:
/* we are now at a leaf device */
xhci_debugfs_remove_slot(xhci, slot_id);
xhci_free_virt_device(xhci, slot_id);
xhci_free_virt_device(xhci, vdev, slot_id);
}
int xhci_alloc_virt_device(struct xhci_hcd *xhci, int slot_id,

9
drivers/usb/host/xhci-ring.c
View File

@ -1592,7 +1592,8 @@ static void xhci_handle_cmd_enable_slot(int slot_id, struct xhci_command *comman
command->slot_id = 0;
}
static void xhci_handle_cmd_disable_slot(struct xhci_hcd *xhci, int slot_id)
static void xhci_handle_cmd_disable_slot(struct xhci_hcd *xhci, int slot_id,
u32 cmd_comp_code)
{
struct xhci_virt_device *virt_dev;
struct xhci_slot_ctx *slot_ctx;
@ -1607,6 +1608,10 @@ static void xhci_handle_cmd_disable_slot(struct xhci_hcd *xhci, int slot_id)
if (xhci->quirks & XHCI_EP_LIMIT_QUIRK)
/* Delete default control endpoint resources */
xhci_free_device_endpoint_resources(xhci, virt_dev, true);
if (cmd_comp_code == COMP_SUCCESS) {
xhci->dcbaa->dev_context_ptrs[slot_id] = 0;
xhci->devs[slot_id] = NULL;
}
}
static void xhci_handle_cmd_config_ep(struct xhci_hcd *xhci, int slot_id)
@ -1856,7 +1861,7 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
xhci_handle_cmd_enable_slot(slot_id, cmd, cmd_comp_code);
break;
case TRB_DISABLE_SLOT:
xhci_handle_cmd_disable_slot(xhci, slot_id);
xhci_handle_cmd_disable_slot(xhci, slot_id, cmd_comp_code);
break;
case TRB_CONFIG_EP:
if (!cmd->completion)

21
drivers/usb/host/xhci.c
View File

@ -3932,8 +3932,7 @@ static int xhci_discover_or_reset_device(struct usb_hcd *hcd,
* Obtaining a new device slot to inform the xHCI host that
* the USB device has been reset.
*/
ret = xhci_disable_slot(xhci, udev->slot_id);
xhci_free_virt_device(xhci, udev->slot_id);
ret = xhci_disable_and_free_slot(xhci, udev->slot_id);
if (!ret) {
ret = xhci_alloc_dev(hcd, udev);
if (ret == 1)
@ -4090,7 +4089,7 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
xhci_disable_slot(xhci, udev->slot_id);
spin_lock_irqsave(&xhci->lock, flags);
xhci_free_virt_device(xhci, udev->slot_id);
xhci_free_virt_device(xhci, virt_dev, udev->slot_id);
spin_unlock_irqrestore(&xhci->lock, flags);
}
@ -4139,6 +4138,16 @@ int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id)
return 0;
}
int xhci_disable_and_free_slot(struct xhci_hcd *xhci, u32 slot_id)
{
struct xhci_virt_device *vdev = xhci->devs[slot_id];
int ret;
ret = xhci_disable_slot(xhci, slot_id);
xhci_free_virt_device(xhci, vdev, slot_id);
return ret;
}
/*
* Checks if we have enough host controller resources for the default control
* endpoint.
@ -4245,8 +4254,7 @@ int xhci_alloc_dev(struct usb_hcd *hcd, struct usb_device *udev)
return 1;
disable_slot:
xhci_disable_slot(xhci, udev->slot_id);
xhci_free_virt_device(xhci, udev->slot_id);
xhci_disable_and_free_slot(xhci, udev->slot_id);
return 0;
}
@ -4382,8 +4390,7 @@ static int xhci_setup_device(struct usb_hcd *hcd, struct usb_device *udev,
dev_warn(&udev->dev, "Device not responding to setup %s.\n", act);
mutex_unlock(&xhci->mutex);
ret = xhci_disable_slot(xhci, udev->slot_id);
xhci_free_virt_device(xhci, udev->slot_id);
ret = xhci_disable_and_free_slot(xhci, udev->slot_id);
if (!ret) {
if (xhci_alloc_dev(hcd, udev) == 1)
xhci_setup_addressable_virt_dev(xhci, udev);

3
drivers/usb/host/xhci.h
View File

@ -1791,7 +1791,7 @@ void xhci_dbg_trace(struct xhci_hcd *xhci, void (*trace)(struct va_format *),
/* xHCI memory management */
void xhci_mem_cleanup(struct xhci_hcd *xhci);
int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags);
void xhci_free_virt_device(struct xhci_hcd *xhci, int slot_id);
void xhci_free_virt_device(struct xhci_hcd *xhci, struct xhci_virt_device *dev, int slot_id);
int xhci_alloc_virt_device(struct xhci_hcd *xhci, int slot_id, struct usb_device *udev, gfp_t flags);
int xhci_setup_addressable_virt_dev(struct xhci_hcd *xhci, struct usb_device *udev);
void xhci_copy_ep0_dequeue_into_input_ctx(struct xhci_hcd *xhci,
@ -1888,6 +1888,7 @@ void xhci_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev);
int xhci_update_hub_device(struct usb_hcd *hcd, struct usb_device *hdev,
struct usb_tt *tt, gfp_t mem_flags);
int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id);
int xhci_disable_and_free_slot(struct xhci_hcd *xhci, u32 slot_id);
int xhci_ext_cap_init(struct xhci_hcd *xhci);
int xhci_suspend(struct xhci_hcd *xhci, bool do_wakeup);