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, 24 insertions, 0 deletions

diff --git a/drivers/usb/phy/Makefile b/drivers/usb/phy/Makefile
new file mode 100644
index 000000000..ceae46c53
--- /dev/null
+++ b/drivers/usb/phy/Makefile
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for physical layer USB drivers
+#
+obj-$(CONFIG_USB_PHY)			+= phy.o
+obj-$(CONFIG_OF)			+= of.o
+
+# transceiver drivers, keep the list sorted
+
+obj-$(CONFIG_AB8500_USB)		+= phy-ab8500-usb.o
+obj-$(CONFIG_FSL_USB2_OTG)		+= phy-fsl-usb.o
+obj-$(CONFIG_NOP_USB_XCEIV)		+= phy-generic.o
+obj-$(CONFIG_TAHVO_USB)			+= phy-tahvo.o
+obj-$(CONFIG_AM335X_CONTROL_USB)	+= phy-am335x-control.o
+obj-$(CONFIG_AM335X_PHY_USB)		+= phy-am335x.o
+obj-$(CONFIG_OMAP_OTG)			+= phy-omap-otg.o
+obj-$(CONFIG_TWL6030_USB)		+= phy-twl6030-usb.o
+obj-$(CONFIG_USB_TEGRA_PHY)		+= phy-tegra-usb.o
+obj-$(CONFIG_USB_GPIO_VBUS)		+= phy-gpio-vbus-usb.o
+obj-$(CONFIG_USB_ISP1301)		+= phy-isp1301.o
+obj-$(CONFIG_USB_MXS_PHY)		+= phy-mxs-usb.o
+obj-$(CONFIG_USB_ULPI)			+= phy-ulpi.o
+obj-$(CONFIG_USB_ULPI_VIEWPORT)		+= phy-ulpi-viewport.o
+obj-$(CONFIG_KEYSTONE_USB_PHY)		+= phy-keystone.o