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/package/gen-diff-patch | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100755 scripts/package/gen-diff-patch (limited to 'scripts/package/gen-diff-patch') diff --git a/scripts/package/gen-diff-patch b/scripts/package/gen-diff-patch new file mode 100755 index 000000000..f272f7770 --- /dev/null +++ b/scripts/package/gen-diff-patch @@ -0,0 +1,38 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-only + +set -eu + +diff_patch=$1 + +mkdir -p "$(dirname "${diff_patch}")" + +git -C "${srctree:-.}" diff HEAD > "${diff_patch}" + +if [ ! -s "${diff_patch}" ] || + [ -z "$(git -C "${srctree:-.}" ls-files --other --exclude-standard | head -n1)" ]; then + exit +fi + +# The source tarball, which is generated by 'git archive', contains everything +# you committed in the repository. If you have local diff ('git diff HEAD'), +# it will go into ${diff_patch}. If untracked files are remaining, the resulting +# source package may not be correct. +# +# Examples: +# - You modified a source file to add #include "new-header.h" +# but forgot to add new-header.h +# - You modified a Makefile to add 'obj-$(CONFIG_FOO) += new-dirver.o' +# but you forgot to add new-driver.c +# +# You need to commit them, or at least stage them by 'git add'. +# +# This script does not take care of untracked files because doing so would +# introduce additional complexity. Instead, print a warning message here if +# untracked files are found. +# If all untracked files are just garbage, you can ignore this warning. +echo >&2 "============================ WARNING ============================" +echo >&2 "Your working tree has diff from HEAD, and also untracked file(s)." +echo >&2 "Please make sure you did 'git add' for all new files you need in" +echo >&2 "the source package." +echo >&2 "=================================================================" -- cgit v1.3.1