From 8a742141f7ab84975aa758b775567ef4740ef0cf Mon Sep 17 00:00:00 2001 From: Chen Pei Date: Wed, 15 Jul 2026 21:50:48 +0800 Subject: [PATCH] ACPI: PCI: Clear driver_data on all paths that free the acpi_pci_root acpi_pci_root_add() assigns the freshly allocated root to device->driver_data before dmar_device_add() and pci_acpi_scan_root(). Both failure paths reach the end: label where root is kfree()'d, but only the pci_acpi_scan_root() path clears driver_data first. When dmar_device_add() fails during a hot-add, root is freed while device->driver_data still points at it. The ACPI core does not clear driver_data on attach failure, so a later acpi_pci_find_root() call may dereference this dangling pointer. acpi_pci_root_remove() has the same problem: it frees root without clearing device->driver_data, leaving a dangling pointer behind after the root bridge is removed. Move the NULL assignment to the shared end: label so every error path in acpi_pci_root_add() clears driver_data before freeing root, and clear it in acpi_pci_root_remove() as well, so the object is never left reachable through driver_data after being freed. Fixes: db89b4f0dbab ("ACPI: catch calls of acpi_driver_data on pointer of wrong type") Reported-by: Sashiko AI review Link: https://sashiko.dev/#/patchset/20260526025118.38935-1-cp0613@linux.alibaba.com Link: https://sashiko.dev/#/patchset/20260707121258.11640-1-cp0613@linux.alibaba.com Signed-off-by: Chen Pei Link: https://patch.msgid.link/20260715135048.3278-1-cp0613@linux.alibaba.com Signed-off-by: Rafael J. Wysocki --- drivers/acpi/pci_root.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c index 4c06c3ffd0cb..408ba12362a7 100644 --- a/drivers/acpi/pci_root.c +++ b/drivers/acpi/pci_root.c @@ -725,7 +725,6 @@ static int acpi_pci_root_add(struct acpi_device *device, dev_err(&device->dev, "Bus %04x:%02x not present in PCI namespace\n", root->segment, (unsigned int)root->secondary.start); - device->driver_data = NULL; result = -ENODEV; goto remove_dmar; } @@ -765,6 +764,7 @@ static int acpi_pci_root_add(struct acpi_device *device, if (hotadd) dmar_device_remove(handle); end: + device->driver_data = NULL; kfree(root); return result; } @@ -788,6 +788,7 @@ static void acpi_pci_root_remove(struct acpi_device *device) pci_unlock_rescan_remove(); + device->driver_data = NULL; kfree(root); }