From 1039bffd6ae9c75b42b7d148d6c1106134107b66 Mon Sep 17 00:00:00 2001 From: Xie Yuanbin Date: Tue, 28 Jul 2026 03:16:42 +0100 Subject: ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults 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 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) Reviewed-by: Linus Walleij Signed-off-by: Qi Xi Signed-off-by: Xie Yuanbin Signed-off-by: Russell King --- scripts/Makefile.clean | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 scripts/Makefile.clean (limited to 'scripts/Makefile.clean') diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean new file mode 100644 index 000000000..6ead00ec7 --- /dev/null +++ b/scripts/Makefile.clean @@ -0,0 +1,63 @@ +# SPDX-License-Identifier: GPL-2.0 +# ========================================================================== +# Cleaning up +# ========================================================================== + +src := $(srcroot)/$(obj) + +PHONY := __clean +__clean: + +include $(srctree)/scripts/Kbuild.include +include $(kbuild-file) + +# Figure out what we need to build from the various variables +# ========================================================================== + +subdir-ymn := $(sort $(subdir-y) $(subdir-m) $(subdir-) \ + $(patsubst %/,%, $(filter %/, $(obj-y) $(obj-m) $(obj-)))) + +# Add subdir path + +subdir-ymn := $(addprefix $(obj)/,$(subdir-ymn)) + +# build a list of files to remove, usually relative to the current +# directory + +__clean-files := \ + $(clean-files) $(targets) $(hostprogs) $(userprogs) \ + $(extra-y) $(extra-m) $(extra-) \ + $(always-y) $(always-m) $(always-) \ + $(hostprogs-always-y) $(hostprogs-always-m) $(hostprogs-always-) \ + $(userprogs-always-y) $(userprogs-always-m) $(userprogs-always-) + +__clean-files := $(filter-out $(no-clean-files), $(__clean-files)) + +__clean-files := $(wildcard $(addprefix $(obj)/, $(__clean-files))) + +# ========================================================================== + +# To make this rule robust against "Argument list too long" error, +# remove $(obj)/ prefix, and restore it by a shell command. +quiet_cmd_clean = CLEAN $(obj) + cmd_clean = printf '$(obj)/%s ' $(patsubst $(obj)/%,%,$(__clean-files)) | xargs rm -rf + +__clean: $(subdir-ymn) +ifneq ($(strip $(__clean-files)),) + $(call cmd,clean) +endif + @: + + +# =========================================================================== +# Generic stuff +# =========================================================================== + +# Descending +# --------------------------------------------------------------------------- + +PHONY += $(subdir-ymn) +$(subdir-ymn): + $(Q)$(MAKE) $(clean)=$@ + +.PHONY: $(PHONY) -- cgit v1.3.1