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 --- lib/zstd/Makefile | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 lib/zstd/Makefile (limited to 'lib/zstd/Makefile') diff --git a/lib/zstd/Makefile b/lib/zstd/Makefile new file mode 100644 index 000000000..be218b5e0 --- /dev/null +++ b/lib/zstd/Makefile @@ -0,0 +1,44 @@ +# SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause +# ################################################################ +# Copyright (c) Meta Platforms, Inc. and affiliates. +# All rights reserved. +# +# This source code is licensed under both the BSD-style license (found in the +# LICENSE file in the root directory of this source tree) and the GPLv2 (found +# in the COPYING file in the root directory of this source tree). +# You may select, at your option, one of the above-listed licenses. +# ################################################################ +obj-$(CONFIG_ZSTD_COMPRESS) += zstd_compress.o +obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd_decompress.o +obj-$(CONFIG_ZSTD_COMMON) += zstd_common.o + +zstd_compress-y := \ + zstd_compress_module.o \ + compress/fse_compress.o \ + compress/hist.o \ + compress/huf_compress.o \ + compress/zstd_compress.o \ + compress/zstd_compress_literals.o \ + compress/zstd_compress_sequences.o \ + compress/zstd_compress_superblock.o \ + compress/zstd_double_fast.o \ + compress/zstd_fast.o \ + compress/zstd_lazy.o \ + compress/zstd_ldm.o \ + compress/zstd_opt.o \ + compress/zstd_preSplit.o \ + +zstd_decompress-y := \ + zstd_decompress_module.o \ + decompress/huf_decompress.o \ + decompress/zstd_ddict.o \ + decompress/zstd_decompress.o \ + decompress/zstd_decompress_block.o \ + +zstd_common-y := \ + zstd_common_module.o \ + common/debug.o \ + common/entropy_common.o \ + common/error_private.o \ + common/fse_decompress.o \ + common/zstd_common.o \ -- cgit v1.3.1