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 --- drivers/rtc/rtc-generic.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 drivers/rtc/rtc-generic.c (limited to 'drivers/rtc/rtc-generic.c') diff --git a/drivers/rtc/rtc-generic.c b/drivers/rtc/rtc-generic.c new file mode 100644 index 000000000..89ae78e93 --- /dev/null +++ b/drivers/rtc/rtc-generic.c @@ -0,0 +1,39 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* rtc-generic: RTC driver using the generic RTC abstraction + * + * Copyright (C) 2008 Kyle McMartin + */ + +#include +#include +#include +#include +#include + +static int __init generic_rtc_probe(struct platform_device *dev) +{ + struct rtc_device *rtc; + const struct rtc_class_ops *ops = dev_get_platdata(&dev->dev); + + rtc = devm_rtc_device_register(&dev->dev, "rtc-generic", + ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + platform_set_drvdata(dev, rtc); + + return 0; +} + +static struct platform_driver generic_rtc_driver = { + .driver = { + .name = "rtc-generic", + }, +}; + +module_platform_driver_probe(generic_rtc_driver, generic_rtc_probe); + +MODULE_AUTHOR("Kyle McMartin "); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Generic RTC driver"); +MODULE_ALIAS("platform:rtc-generic"); -- cgit v1.3.1