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/trace/misc/fsnotify.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 include/trace/misc/fsnotify.h (limited to 'include/trace/misc/fsnotify.h') diff --git a/include/trace/misc/fsnotify.h b/include/trace/misc/fsnotify.h new file mode 100644 index 000000000..a201e1bd6 --- /dev/null +++ b/include/trace/misc/fsnotify.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Display helpers for fsnotify events + */ + +#include + +#define show_fsnotify_mask(mask) \ + __print_flags(mask, "|", \ + { FS_ACCESS, "ACCESS" }, \ + { FS_MODIFY, "MODIFY" }, \ + { FS_ATTRIB, "ATTRIB" }, \ + { FS_CLOSE_WRITE, "CLOSE_WRITE" }, \ + { FS_CLOSE_NOWRITE, "CLOSE_NOWRITE" }, \ + { FS_OPEN, "OPEN" }, \ + { FS_MOVED_FROM, "MOVED_FROM" }, \ + { FS_MOVED_TO, "MOVED_TO" }, \ + { FS_CREATE, "CREATE" }, \ + { FS_DELETE, "DELETE" }, \ + { FS_DELETE_SELF, "DELETE_SELF" }, \ + { FS_MOVE_SELF, "MOVE_SELF" }, \ + { FS_OPEN_EXEC, "OPEN_EXEC" }, \ + { FS_UNMOUNT, "UNMOUNT" }, \ + { FS_Q_OVERFLOW, "Q_OVERFLOW" }, \ + { FS_ERROR, "ERROR" }, \ + { FS_OPEN_PERM, "OPEN_PERM" }, \ + { FS_ACCESS_PERM, "ACCESS_PERM" }, \ + { FS_OPEN_EXEC_PERM, "OPEN_EXEC_PERM" }, \ + { FS_PRE_ACCESS, "PRE_ACCESS" }, \ + { FS_MNT_ATTACH, "MNT_ATTACH" }, \ + { FS_MNT_DETACH, "MNT_DETACH" }, \ + { FS_EVENT_ON_CHILD, "EVENT_ON_CHILD" }, \ + { FS_RENAME, "RENAME" }, \ + { FS_DN_MULTISHOT, "DN_MULTISHOT" }, \ + { FS_ISDIR, "ISDIR" }) -- cgit v1.3.1