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 --- sound/soc/sof/sof-utils.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 sound/soc/sof/sof-utils.h (limited to 'sound/soc/sof/sof-utils.h') diff --git a/sound/soc/sof/sof-utils.h b/sound/soc/sof/sof-utils.h new file mode 100644 index 000000000..9ac6de9a6 --- /dev/null +++ b/sound/soc/sof/sof-utils.h @@ -0,0 +1,19 @@ +/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */ +/* + * This file is provided under a dual BSD/GPLv2 license. When using or + * redistributing this file, you may do so under either license. + * + * Copyright(c) 2022 Intel Corporation + */ + +#ifndef __SOC_SOF_UTILS_H +#define __SOC_SOF_UTILS_H + +struct snd_dma_buffer; +struct device; + +int snd_sof_create_page_table(struct device *dev, + struct snd_dma_buffer *dmab, + unsigned char *page_table, size_t size); + +#endif -- cgit v1.3.1