The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 2eb03376151bb8585caa23ed2673583107bb5193 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025082308-crafty-citable-521f@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 2eb03376151bb8585caa23ed2673583107bb5193 Mon Sep 17 00:00:00 2001 From: Weitao Wang WeitaoWang-oc@zhaoxin.com Date: Tue, 19 Aug 2025 15:58:43 +0300 Subject: [PATCH] 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: 7faac1953ed1 ("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... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c index 92bb84f8132a..b3a59ce1b3f4 100644 --- a/drivers/usb/host/xhci-hub.c +++ b/drivers/usb/host/xhci-hub.c @@ -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); diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index 07289333a1e8..81eaad87a3d9 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -865,21 +865,20 @@ int xhci_alloc_tt_info(struct xhci_hcd *xhci, * 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, diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index ecd757d482c5..4f8f5aab109d 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -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) diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 47151ca527bf..0e03691f03bf 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -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); diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index a20f4e7cd43a..85d5b964bf1e 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -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);