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, 41 insertions, 0 deletions

diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
new file mode 100644
index 000000000..3ee883c87
--- /dev/null
+++ b/drivers/memory/Makefile
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for memory devices
+#
+
+obj-$(CONFIG_DDR)		+= jedec_ddr_data.o
+ifeq ($(CONFIG_DDR),y)
+obj-$(CONFIG_OF)		+= of_memory.o
+endif
+obj-$(CONFIG_ARM_PL172_MPMC)	+= pl172.o
+obj-$(CONFIG_ATMEL_EBI)		+= atmel-ebi.o
+obj-$(CONFIG_BRCMSTB_DPFE)	+= brcmstb_dpfe.o
+obj-$(CONFIG_BRCMSTB_MEMC)	+= brcmstb_memc.o
+obj-$(CONFIG_TI_AEMIF)		+= ti-aemif.o
+obj-$(CONFIG_TI_EMIF)		+= emif.o
+obj-$(CONFIG_OMAP_GPMC)		+= omap-gpmc.o
+obj-$(CONFIG_FSL_CORENET_CF)	+= fsl-corenet-cf.o
+obj-$(CONFIG_FSL_IFC)		+= fsl_ifc.o
+obj-$(CONFIG_MVEBU_DEVBUS)	+= mvebu-devbus.o
+obj-$(CONFIG_JZ4780_NEMC)	+= jz4780-nemc.o
+obj-$(CONFIG_MTK_SMI)		+= mtk-smi.o
+obj-$(CONFIG_DA8XX_DDRCTL)	+= da8xx-ddrctl.o
+obj-$(CONFIG_PL353_SMC)		+= pl353-smc.o
+obj-$(CONFIG_RENESAS_RPCIF)	+= renesas-rpc-if.o
+obj-$(CONFIG_STM32_FMC2_EBI)	+= stm32-fmc2-ebi.o
+obj-$(CONFIG_STM32_OMM)		+= stm32_omm.o
+
+obj-$(CONFIG_SAMSUNG_MC)	+= samsung/
+obj-$(CONFIG_TEGRA_MC)		+= tegra/
+obj-$(CONFIG_TI_EMIF_SRAM)	+= ti-emif-sram.o
+obj-$(CONFIG_FPGA_DFL_EMIF)	+= dfl-emif.o
+
+ti-emif-sram-objs		:= ti-emif-pm.o ti-emif-sram-pm.o
+
+$(obj)/ti-emif-sram-pm.o: $(obj)/ti-emif-asm-offsets.h
+
+$(obj)/ti-emif-asm-offsets.h: $(obj)/emif-asm-offsets.s FORCE
+	$(call filechk,offsets,__TI_EMIF_ASM_OFFSETS_H__)
+
+targets += emif-asm-offsets.s
+clean-files += ti-emif-asm-offsets.h