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/phy/mediatek/Makefile b/drivers/phy/mediatek/Makefile
new file mode 100644
index 000000000..1b8088df7
--- /dev/null
+++ b/drivers/phy/mediatek/Makefile
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the phy drivers.
+#
+
+obj-$(CONFIG_PHY_MTK_DP)		+= phy-mtk-dp.o
+obj-$(CONFIG_PHY_MTK_PCIE)		+= phy-mtk-pcie.o
+obj-$(CONFIG_PHY_MTK_TPHY)		+= phy-mtk-tphy.o
+obj-$(CONFIG_PHY_MTK_UFS)		+= phy-mtk-ufs.o
+obj-$(CONFIG_PHY_MTK_XSPHY)		+= phy-mtk-xsphy.o
+obj-$(CONFIG_PHY_MTK_XFI_TPHY)		+= phy-mtk-xfi-tphy.o
+
+phy-mtk-hdmi-drv-y			:= phy-mtk-hdmi.o
+phy-mtk-hdmi-drv-y			+= phy-mtk-hdmi-mt2701.o
+phy-mtk-hdmi-drv-y			+= phy-mtk-hdmi-mt8173.o
+phy-mtk-hdmi-drv-y			+= phy-mtk-hdmi-mt8195.o
+obj-$(CONFIG_PHY_MTK_HDMI)		+= phy-mtk-hdmi-drv.o
+
+obj-$(CONFIG_PHY_MTK_MIPI_CSI_0_5)	+= phy-mtk-mipi-csi-0-5.o
+
+phy-mtk-mipi-dsi-drv-y			:= phy-mtk-mipi-dsi.o
+phy-mtk-mipi-dsi-drv-y			+= phy-mtk-mipi-dsi-mt8173.o
+phy-mtk-mipi-dsi-drv-y			+= phy-mtk-mipi-dsi-mt8183.o
+obj-$(CONFIG_PHY_MTK_MIPI_DSI)		+= phy-mtk-mipi-dsi-drv.o