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, 86 insertions, 0 deletions

diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
new file mode 100644
index 000000000..944d8ea39
--- /dev/null
+++ b/drivers/mailbox/Makefile
@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: GPL-2.0
+# Generic MAILBOX API
+
+obj-$(CONFIG_MAILBOX)		+= mailbox.o
+
+obj-$(CONFIG_MAILBOX_TEST)	+= mailbox-test.o
+
+obj-$(CONFIG_ARM_MHU)	+= arm_mhu.o arm_mhu_db.o
+
+obj-$(CONFIG_ARM_MHU_V2)	+= arm_mhuv2.o
+
+obj-$(CONFIG_ARM_MHU_V3)	+= arm_mhuv3.o
+
+obj-$(CONFIG_AST2700_MBOX)	+= ast2700-mailbox.o
+
+obj-$(CONFIG_CV1800_MBOX)	+= cv1800-mailbox.o
+
+obj-$(CONFIG_EXYNOS_MBOX)	+= exynos-mailbox.o
+
+obj-$(CONFIG_IMX_MBOX)	+= imx-mailbox.o
+
+obj-$(CONFIG_ARMADA_37XX_RWTM_MBOX)	+= armada-37xx-rwtm-mailbox.o
+
+obj-$(CONFIG_PLATFORM_MHU)	+= platform_mhu.o
+
+obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
+
+obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o
+
+obj-$(CONFIG_ROCKCHIP_MBOX)	+= rockchip-mailbox.o
+
+obj-$(CONFIG_PCC)		+= pcc.o
+
+obj-$(CONFIG_ALTERA_MBOX)	+= mailbox-altera.o
+
+obj-$(CONFIG_BCM2835_MBOX)	+= bcm2835-mailbox.o
+
+obj-$(CONFIG_STI_MBOX)		+= mailbox-sti.o
+
+obj-$(CONFIG_TI_MESSAGE_MANAGER) += ti-msgmgr.o
+
+obj-$(CONFIG_XGENE_SLIMPRO_MBOX) += mailbox-xgene-slimpro.o
+
+obj-$(CONFIG_HI3660_MBOX)	+= hi3660-mailbox.o
+
+obj-$(CONFIG_HI6220_MBOX)	+= hi6220-mailbox.o
+
+obj-$(CONFIG_BCM_PDC_MBOX)	+= bcm-pdc-mailbox.o
+
+obj-$(CONFIG_BCM_FLEXRM_MBOX)	+= bcm-flexrm-mailbox.o
+
+obj-$(CONFIG_POLARFIRE_SOC_MAILBOX)	+= mailbox-mpfs.o
+
+obj-$(CONFIG_MCHP_SBI_IPC_MBOX)		+= mailbox-mchp-ipc-sbi.o
+
+obj-$(CONFIG_QCOM_APCS_IPC)	+= qcom-apcs-ipc-mailbox.o
+
+obj-$(CONFIG_TEGRA_HSP_MBOX)	+= tegra-hsp.o
+
+obj-$(CONFIG_STM32_IPCC) 	+= stm32-ipcc.o
+
+obj-$(CONFIG_MTK_ADSP_MBOX)	+= mtk-adsp-mailbox.o
+
+obj-$(CONFIG_MTK_CMDQ_MBOX)	+= mtk-cmdq-mailbox.o
+
+obj-$(CONFIG_MTK_GPUEB_MBOX)	+= mtk-gpueb-mailbox.o
+
+obj-$(CONFIG_MTK_VCP_MBOX)	+= mtk-vcp-mailbox.o
+
+obj-$(CONFIG_ZYNQMP_IPI_MBOX)	+= zynqmp-ipi-mailbox.o
+
+obj-$(CONFIG_SUN6I_MSGBOX)	+= sun6i-msgbox.o
+
+obj-$(CONFIG_SPRD_MBOX)		+= sprd-mailbox.o
+
+obj-$(CONFIG_QCOM_CPUCP_MBOX)	+= qcom-cpucp-mbox.o
+
+obj-$(CONFIG_QCOM_IPCC)		+= qcom-ipcc.o
+
+obj-$(CONFIG_THEAD_TH1520_MBOX)	+= mailbox-th1520.o
+
+obj-$(CONFIG_CIX_MBOX)	+= cix-mailbox.o
+
+obj-$(CONFIG_BCM74110_MAILBOX)	+= bcm74110-mailbox.o
+
+obj-$(CONFIG_RISCV_SBI_MPXY_MBOX)	+= riscv-sbi-mpxy-mbox.o