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 --- security/Makefile | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) create mode 100644 security/Makefile (limited to 'security/Makefile') diff --git a/security/Makefile b/security/Makefile new file mode 100644 index 000000000..4601230ba --- /dev/null +++ b/security/Makefile @@ -0,0 +1,31 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Makefile for the kernel security code +# + +obj-$(CONFIG_KEYS) += keys/ + +# always enable default capabilities +obj-y += commoncap.o +obj-$(CONFIG_SECURITY) += lsm_syscalls.o +obj-$(CONFIG_MMU) += min_addr.o + +# Object file lists +obj-$(CONFIG_SECURITY) += security.o lsm_notifier.o lsm_init.o +obj-$(CONFIG_SECURITYFS) += inode.o +obj-$(CONFIG_SECURITY_SELINUX) += selinux/ +obj-$(CONFIG_SECURITY_SMACK) += smack/ +obj-$(CONFIG_HAS_SECURITY_AUDIT) += lsm_audit.o +obj-$(CONFIG_SECURITY_TOMOYO) += tomoyo/ +obj-$(CONFIG_SECURITY_APPARMOR) += apparmor/ +obj-$(CONFIG_SECURITY_YAMA) += yama/ +obj-$(CONFIG_SECURITY_LOADPIN) += loadpin/ +obj-$(CONFIG_SECURITY_SAFESETID) += safesetid/ +obj-$(CONFIG_SECURITY_LOCKDOWN_LSM) += lockdown/ +obj-$(CONFIG_CGROUPS) += device_cgroup.o +obj-$(CONFIG_BPF_LSM) += bpf/ +obj-$(CONFIG_SECURITY_LANDLOCK) += landlock/ +obj-$(CONFIG_SECURITY_IPE) += ipe/ + +# Object integrity file lists +obj-$(CONFIG_INTEGRITY) += integrity/ -- cgit v1.3.1