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-aspeed.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 130 insertions(+) create mode 100644 drivers/rtc/rtc-aspeed.c (limited to 'drivers/rtc/rtc-aspeed.c') diff --git a/drivers/rtc/rtc-aspeed.c b/drivers/rtc/rtc-aspeed.c new file mode 100644 index 000000000..8f5b440f8 --- /dev/null +++ b/drivers/rtc/rtc-aspeed.c @@ -0,0 +1,130 @@ +// SPDX-License-Identifier: GPL-2.0+ +// Copyright 2015 IBM Corp. + +#include +#include +#include +#include +#include + +struct aspeed_rtc { + void __iomem *base; +}; + +#define RTC_TIME 0x00 +#define RTC_YEAR 0x04 +#define RTC_CTRL 0x10 + +#define RTC_UNLOCK BIT(1) +#define RTC_ENABLE BIT(0) + +static int aspeed_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + struct aspeed_rtc *rtc = dev_get_drvdata(dev); + unsigned int cent, year; + u32 reg1, reg2; + + if (!(readl(rtc->base + RTC_CTRL) & RTC_ENABLE)) { + dev_dbg(dev, "%s failing as rtc disabled\n", __func__); + return -EINVAL; + } + + do { + reg2 = readl(rtc->base + RTC_YEAR); + reg1 = readl(rtc->base + RTC_TIME); + } while (reg2 != readl(rtc->base + RTC_YEAR)); + + tm->tm_mday = (reg1 >> 24) & 0x1f; + tm->tm_hour = (reg1 >> 16) & 0x1f; + tm->tm_min = (reg1 >> 8) & 0x3f; + tm->tm_sec = (reg1 >> 0) & 0x3f; + + cent = (reg2 >> 16) & 0x1f; + year = (reg2 >> 8) & 0x7f; + tm->tm_mon = ((reg2 >> 0) & 0x0f) - 1; + tm->tm_year = year + (cent * 100) - 1900; + + dev_dbg(dev, "%s %ptR", __func__, tm); + + return 0; +} + +static int aspeed_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct aspeed_rtc *rtc = dev_get_drvdata(dev); + u32 reg1, reg2, ctrl; + int year, cent; + + cent = (tm->tm_year + 1900) / 100; + year = tm->tm_year % 100; + + reg1 = (tm->tm_mday << 24) | (tm->tm_hour << 16) | (tm->tm_min << 8) | + tm->tm_sec; + + reg2 = ((cent & 0x1f) << 16) | ((year & 0x7f) << 8) | + ((tm->tm_mon + 1) & 0xf); + + ctrl = readl(rtc->base + RTC_CTRL); + writel(ctrl | RTC_UNLOCK, rtc->base + RTC_CTRL); + + writel(reg1, rtc->base + RTC_TIME); + writel(reg2, rtc->base + RTC_YEAR); + + /* Re-lock and ensure enable is set now that a time is programmed */ + writel(ctrl | RTC_ENABLE, rtc->base + RTC_CTRL); + + return 0; +} + +static const struct rtc_class_ops aspeed_rtc_ops = { + .read_time = aspeed_rtc_read_time, + .set_time = aspeed_rtc_set_time, +}; + +static int aspeed_rtc_probe(struct platform_device *pdev) +{ + struct aspeed_rtc *rtc; + struct rtc_device *rtc_dev; + + rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL); + if (!rtc) + return -ENOMEM; + + rtc->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(rtc->base)) + return PTR_ERR(rtc->base); + + rtc_dev = devm_rtc_allocate_device(&pdev->dev); + if (IS_ERR(rtc_dev)) + return PTR_ERR(rtc_dev); + + platform_set_drvdata(pdev, rtc); + + rtc_dev->ops = &aspeed_rtc_ops; + rtc_dev->range_min = RTC_TIMESTAMP_BEGIN_1900; + rtc_dev->range_max = 38814989399LL; /* 3199-12-31 23:59:59 */ + + return devm_rtc_register_device(rtc_dev); +} + +static const struct of_device_id aspeed_rtc_match[] = { + { .compatible = "aspeed,ast2400-rtc", }, + { .compatible = "aspeed,ast2500-rtc", }, + { .compatible = "aspeed,ast2600-rtc", }, + { .compatible = "aspeed,ast2700-rtc", }, + {} +}; +MODULE_DEVICE_TABLE(of, aspeed_rtc_match); + +static struct platform_driver aspeed_rtc_driver = { + .driver = { + .name = "aspeed-rtc", + .of_match_table = aspeed_rtc_match, + }, +}; + +module_platform_driver_probe(aspeed_rtc_driver, aspeed_rtc_probe); + +MODULE_DESCRIPTION("ASPEED RTC driver"); +MODULE_AUTHOR("Joel Stanley "); +MODULE_LICENSE("GPL"); -- cgit v1.3.1