From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- include/drm/drm_util.h | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 include/drm/drm_util.h (limited to 'include/drm/drm_util.h') diff --git a/include/drm/drm_util.h b/include/drm/drm_util.h new file mode 100644 index 000000000..440199618 --- /dev/null +++ b/include/drm/drm_util.h @@ -0,0 +1,69 @@ +/* + * Internal Header for the Direct Rendering Manager + * + * Copyright 2018 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + */ + +#ifndef _DRM_UTIL_H_ +#define _DRM_UTIL_H_ + +/** + * DOC: drm utils + * + * Macros and inline functions that does not naturally belong in other places + */ + +#include +#include +#include +#include +#include + +/* + * Use EXPORT_SYMBOL_FOR_TESTS_ONLY() for functions that shall + * only be visible for drmselftests. + */ +#if defined(CONFIG_DRM_EXPORT_FOR_TESTS) +#define EXPORT_SYMBOL_FOR_TESTS_ONLY(x) EXPORT_SYMBOL(x) +#else +#define EXPORT_SYMBOL_FOR_TESTS_ONLY(x) +#endif + +/** + * drm_can_sleep - returns true if currently okay to sleep + * + * This function shall not be used in new code. + * The check for running in atomic context may not work - see linux/preempt.h. + * + * FIXME: All users of drm_can_sleep should be removed (see todo.rst) + * + * Returns: + * False if kgdb is active, we are in atomic context or irqs are disabled. + */ +static inline bool drm_can_sleep(void) +{ + if (in_atomic() || in_dbg_master() || irqs_disabled()) + return false; + return true; +} + +#endif -- cgit v1.3.1