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 --- include/uapi/asm-generic/errno-base.h | 40 +++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 include/uapi/asm-generic/errno-base.h (limited to 'include/uapi/asm-generic/errno-base.h') diff --git a/include/uapi/asm-generic/errno-base.h b/include/uapi/asm-generic/errno-base.h new file mode 100644 index 000000000..9653140bf --- /dev/null +++ b/include/uapi/asm-generic/errno-base.h @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _ASM_GENERIC_ERRNO_BASE_H +#define _ASM_GENERIC_ERRNO_BASE_H + +#define EPERM 1 /* Operation not permitted */ +#define ENOENT 2 /* No such file or directory */ +#define ESRCH 3 /* No such process */ +#define EINTR 4 /* Interrupted system call */ +#define EIO 5 /* I/O error */ +#define ENXIO 6 /* No such device or address */ +#define E2BIG 7 /* Argument list too long */ +#define ENOEXEC 8 /* Exec format error */ +#define EBADF 9 /* Bad file number */ +#define ECHILD 10 /* No child processes */ +#define EAGAIN 11 /* Try again */ +#define ENOMEM 12 /* Out of memory */ +#define EACCES 13 /* Permission denied */ +#define EFAULT 14 /* Bad address */ +#define ENOTBLK 15 /* Block device required */ +#define EBUSY 16 /* Device or resource busy */ +#define EEXIST 17 /* File exists */ +#define EXDEV 18 /* Cross-device link */ +#define ENODEV 19 /* No such device */ +#define ENOTDIR 20 /* Not a directory */ +#define EISDIR 21 /* Is a directory */ +#define EINVAL 22 /* Invalid argument */ +#define ENFILE 23 /* File table overflow */ +#define EMFILE 24 /* Too many open files */ +#define ENOTTY 25 /* Not a typewriter */ +#define ETXTBSY 26 /* Text file busy */ +#define EFBIG 27 /* File too large */ +#define ENOSPC 28 /* No space left on device */ +#define ESPIPE 29 /* Illegal seek */ +#define EROFS 30 /* Read-only file system */ +#define EMLINK 31 /* Too many links */ +#define EPIPE 32 /* Broken pipe */ +#define EDOM 33 /* Math argument out of domain of func */ +#define ERANGE 34 /* Math result not representable */ + +#endif -- cgit v1.3.1