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 --- drivers/input/input-compat.h | 81 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 drivers/input/input-compat.h (limited to 'drivers/input/input-compat.h') diff --git a/drivers/input/input-compat.h b/drivers/input/input-compat.h new file mode 100644 index 000000000..99c87ceb9 --- /dev/null +++ b/drivers/input/input-compat.h @@ -0,0 +1,81 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _INPUT_COMPAT_H +#define _INPUT_COMPAT_H + +/* + * 32bit compatibility wrappers for the input subsystem. + * + * Very heavily based on evdev.c - Copyright (c) 1999-2002 Vojtech Pavlik + */ + +#include +#include +#include + +#ifdef CONFIG_COMPAT + +struct input_event_compat { + compat_ulong_t sec; + compat_ulong_t usec; + __u16 type; + __u16 code; + __s32 value; +}; + +struct ff_periodic_effect_compat { + __u16 waveform; + __u16 period; + __s16 magnitude; + __s16 offset; + __u16 phase; + + struct ff_envelope envelope; + + __u32 custom_len; + compat_uptr_t custom_data; +}; + +struct ff_effect_compat { + __u16 type; + __s16 id; + __u16 direction; + struct ff_trigger trigger; + struct ff_replay replay; + + union { + struct ff_constant_effect constant; + struct ff_ramp_effect ramp; + struct ff_periodic_effect_compat periodic; + struct ff_condition_effect condition[2]; /* One for each axis */ + struct ff_rumble_effect rumble; + } u; +}; + +static inline size_t input_event_size(void) +{ + return (in_compat_syscall() && !COMPAT_USE_64BIT_TIME) ? + sizeof(struct input_event_compat) : sizeof(struct input_event); +} + +#else + +static inline size_t input_event_size(void) +{ + return sizeof(struct input_event); +} + +#endif /* CONFIG_COMPAT */ + +int input_event_from_user(const char __user *buffer, + struct input_event *event); + +int input_event_to_user(char __user *buffer, + const struct input_event *event); + +int input_ff_effect_from_user(const char __user *buffer, size_t size, + struct ff_effect *effect); + +int input_bits_to_string(char *buf, int buf_size, unsigned long bits, + bool skip_empty); + +#endif /* _INPUT_COMPAT_H */ -- cgit v1.3.1