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/Kbuild | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 include/uapi/asm-generic/Kbuild (limited to 'include/uapi/asm-generic/Kbuild') diff --git a/include/uapi/asm-generic/Kbuild b/include/uapi/asm-generic/Kbuild new file mode 100644 index 000000000..ebb180aac --- /dev/null +++ b/include/uapi/asm-generic/Kbuild @@ -0,0 +1,36 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Headers that are mandatory in usr/include/asm/ +# (This file is not included when SRCARCH=um since UML does not support UAPI.) + +mandatory-y += auxvec.h +mandatory-y += bitsperlong.h +mandatory-y += bpf_perf_event.h +mandatory-y += byteorder.h +mandatory-y += errno.h +mandatory-y += fcntl.h +mandatory-y += ioctl.h +mandatory-y += ioctls.h +mandatory-y += ipcbuf.h +mandatory-y += mman.h +mandatory-y += msgbuf.h +mandatory-y += param.h +mandatory-y += poll.h +mandatory-y += posix_types.h +mandatory-y += ptrace.h +mandatory-y += resource.h +mandatory-y += sembuf.h +mandatory-y += setup.h +mandatory-y += shmbuf.h +mandatory-y += sigcontext.h +mandatory-y += siginfo.h +mandatory-y += signal.h +mandatory-y += socket.h +mandatory-y += sockios.h +mandatory-y += stat.h +mandatory-y += statfs.h +mandatory-y += swab.h +mandatory-y += termbits.h +mandatory-y += termios.h +mandatory-y += types.h +mandatory-y += unistd.h -- cgit v1.3.1