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, 90 insertions, 0 deletions

diff --git a/drivers/input/tablet/Kconfig b/drivers/input/tablet/Kconfig
new file mode 100644
index 000000000..ec27eff6a
--- /dev/null
+++ b/drivers/input/tablet/Kconfig
@@ -0,0 +1,90 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Tablet driver configuration
+#
+menuconfig INPUT_TABLET
+	bool "Tablets"
+	help
+	  Say Y here, and a list of supported tablets will be displayed.
+	  This option doesn't affect the kernel.
+
+	  If unsure, say Y.
+
+if INPUT_TABLET
+
+config TABLET_USB_ACECAD
+	tristate "Acecad Flair tablet support (USB)"
+	depends on USB_ARCH_HAS_HCD
+	select USB
+	help
+	  Say Y here if you want to use the USB version of the Acecad Flair
+	  tablet.  Make sure to say Y to "Mouse support"
+	  (CONFIG_INPUT_MOUSEDEV) and/or "Event interface support"
+	  (CONFIG_INPUT_EVDEV) as well.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called acecad.
+
+config TABLET_USB_AIPTEK
+	tristate "Aiptek 6000U/8000U and Genius G_PEN tablet support (USB)"
+	depends on USB_ARCH_HAS_HCD
+	select USB
+	help
+	  Say Y here if you want to use the USB version of the Aiptek 6000U,
+	  Aiptek 8000U or Genius G-PEN 560 tablet.  Make sure to say Y to
+	  "Mouse support" (CONFIG_INPUT_MOUSEDEV) and/or "Event interface
+	  support" (CONFIG_INPUT_EVDEV) as well.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called aiptek.
+
+config TABLET_USB_HANWANG
+	tristate "Hanwang Art Master III tablet support (USB)"
+	depends on USB_ARCH_HAS_HCD
+	select USB
+	help
+	  Say Y here if you want to use the USB version of the Hanwang Art
+	  Master III tablet.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hanwang.
+
+config TABLET_USB_KBTAB
+	tristate "KB Gear JamStudio tablet support (USB)"
+	depends on USB_ARCH_HAS_HCD
+	select USB
+	help
+	  Say Y here if you want to use the USB version of the KB Gear
+	  JamStudio tablet.  Make sure to say Y to "Mouse support"
+	  (CONFIG_INPUT_MOUSEDEV) and/or "Event interface support"
+	  (CONFIG_INPUT_EVDEV) as well.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called kbtab.
+
+config TABLET_USB_PEGASUS
+	tristate "Pegasus Mobile Notetaker Pen input tablet support"
+	depends on USB_ARCH_HAS_HCD
+	select USB
+	help
+	  Say Y here if you want to use the Pegasus Mobile Notetaker,
+	  also known as:
+	  Genie e-note The Notetaker,
+	  Staedtler Digital ballpoint pen 990 01,
+	  IRISnotes Express or
+	  NEWLink Digital Note Taker.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called pegasus_notetaker.
+
+config TABLET_SERIAL_WACOM4
+	tristate "Wacom protocol 4 serial tablet support"
+	select SERIO
+	help
+	  Say Y here if you want to use Wacom protocol 4 serial tablets.
+	  E.g. serial versions of the Cintiq, Graphire or Penpartner.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called wacom_serial4.
+
+endif