ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faultsgrafted

When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
a user fault may trigger show_pte() without any lock.
If another thread in the same process concurrently calls munmap(),
the page table pages may be freed while show_pte() is still traversing
them, causing a use-after-free in show_pte().

If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table
of PMD are freed when show_pte() is running.

Acquire mmap_write_lock() around show_pte() for user faults to fix the
contention.

For user faults, additionally restrict that show_pte() is called only
when the addr is a user-space address (addr < TASK_SIZE). This is because
the lock of tsk->mm only protects the virtual memory of user address space,
furthermore, dumping the page tables of a kernel-space address for user
faults is unnecessary and may have security implications.

Keep everything unchanged for kernel faults, because the kernel is
already in the "oops" state, acquiring a lock may risk a deadlock.

Co-developed-by: Qi Xi <xiqi2@huawei.com>

Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults")
Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
new file mode 100644
index 000000000..494ab0377
--- /dev/null
+++ b/drivers/usb/misc/Makefile
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the rest of the USB drivers
+# (the ones that don't fit into any other categories)
+#
+obj-$(CONFIG_USB_ADUTUX)		+= adutux.o
+obj-$(CONFIG_USB_APPLEDISPLAY)		+= appledisplay.o
+obj-$(CONFIG_USB_CYPRESS_CY7C63)	+= cypress_cy7c63.o
+obj-$(CONFIG_USB_CYTHERM)		+= cytherm.o
+obj-$(CONFIG_USB_EMI26)			+= emi26.o
+obj-$(CONFIG_USB_EMI62)			+= emi62.o
+obj-$(CONFIG_USB_EZUSB_FX2)		+= ezusb.o
+obj-$(CONFIG_APPLE_MFI_FASTCHARGE)	+= apple-mfi-fastcharge.o
+obj-$(CONFIG_USB_LJCA)			+= usb-ljca.o
+obj-$(CONFIG_USB_USBIO)			+= usbio.o
+obj-$(CONFIG_USB_IDMOUSE)		+= idmouse.o
+obj-$(CONFIG_USB_IOWARRIOR)		+= iowarrior.o
+obj-$(CONFIG_USB_ISIGHTFW)		+= isight_firmware.o
+obj-$(CONFIG_USB_LCD)			+= usblcd.o
+obj-$(CONFIG_USB_LD)			+= ldusb.o
+obj-$(CONFIG_USB_LEGOTOWER)		+= legousbtower.o
+obj-$(CONFIG_USB_QCOM_EUD)		+= qcom_eud.o
+obj-$(CONFIG_USB_TEST)			+= usbtest.o
+obj-$(CONFIG_USB_EHSET_TEST_FIXTURE)    += ehset.o
+obj-$(CONFIG_USB_TRANCEVIBRATOR)	+= trancevibrator.o
+obj-$(CONFIG_USB_USS720)		+= uss720.o
+obj-$(CONFIG_USB_SEVSEG)		+= usbsevseg.o
+obj-$(CONFIG_USB_YUREX)			+= yurex.o
+obj-$(CONFIG_USB_HUB_USB251XB)		+= usb251xb.o
+obj-$(CONFIG_USB_HSIC_USB3503)		+= usb3503.o
+obj-$(CONFIG_USB_HSIC_USB4604)		+= usb4604.o
+obj-$(CONFIG_USB_CHAOSKEY)		+= chaoskey.o
+
+obj-$(CONFIG_USB_SISUSBVGA)		+= sisusbvga/
+obj-$(CONFIG_USB_LINK_LAYER_TEST)	+= lvstest.o
+obj-$(CONFIG_BRCM_USB_PINMAP)		+= brcmstb-usb-pinmap.o
+obj-$(CONFIG_USB_ONBOARD_DEV)		+= onboard_usb_dev.o