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/proc.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 drivers/rtc/proc.c (limited to 'drivers/rtc/proc.c') diff --git a/drivers/rtc/proc.c b/drivers/rtc/proc.c new file mode 100644 index 000000000..cbcdbb19d --- /dev/null +++ b/drivers/rtc/proc.c @@ -0,0 +1,92 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * RTC subsystem, proc interface + * + * Copyright (C) 2005-06 Tower Technologies + * Author: Alessandro Zummo + * + * based on arch/arm/common/rtctime.c + */ + +#include +#include +#include +#include + +#include "rtc-core.h" + +#define NAME_SIZE 10 + +#if defined(CONFIG_RTC_HCTOSYS_DEVICE) +static bool is_rtc_hctosys(struct rtc_device *rtc) +{ + int size; + char name[NAME_SIZE]; + + size = snprintf(name, NAME_SIZE, "rtc%d", rtc->id); + if (size >= NAME_SIZE) + return false; + + return !strncmp(name, CONFIG_RTC_HCTOSYS_DEVICE, NAME_SIZE); +} +#else +static bool is_rtc_hctosys(struct rtc_device *rtc) +{ + return (rtc->id == 0); +} +#endif + +static int rtc_proc_show(struct seq_file *seq, void *offset) +{ + int err; + struct rtc_device *rtc = seq->private; + const struct rtc_class_ops *ops = rtc->ops; + struct rtc_wkalrm alrm; + struct rtc_time tm; + + err = rtc_read_time(rtc, &tm); + if (err == 0) { + seq_printf(seq, + "rtc_time\t: %ptRt\n" + "rtc_date\t: %ptRd\n", + &tm, &tm); + } + + err = rtc_read_alarm(rtc, &alrm); + if (err == 0) { + seq_printf(seq, "alrm_time\t: %ptRt\n", &alrm.time); + seq_printf(seq, "alrm_date\t: %ptRd\n", &alrm.time); + seq_printf(seq, "alarm_IRQ\t: %s\n", + alrm.enabled ? "yes" : "no"); + seq_printf(seq, "alrm_pending\t: %s\n", + alrm.pending ? "yes" : "no"); + seq_printf(seq, "update IRQ enabled\t: %s\n", + (rtc->uie_rtctimer.enabled) ? "yes" : "no"); + seq_printf(seq, "periodic IRQ enabled\t: %s\n", + (rtc->pie_enabled) ? "yes" : "no"); + seq_printf(seq, "periodic IRQ frequency\t: %d\n", + rtc->irq_freq); + seq_printf(seq, "max user IRQ frequency\t: %d\n", + rtc->max_user_freq); + } + + seq_printf(seq, "24hr\t\t: yes\n"); + + if (ops->proc) + ops->proc(rtc->dev.parent, seq); + + return 0; +} + +void rtc_proc_add_device(struct rtc_device *rtc) +{ + if (is_rtc_hctosys(rtc)) + proc_create_single_data("driver/rtc", 0, NULL, rtc_proc_show, + rtc); +} + +void rtc_proc_del_device(struct rtc_device *rtc) +{ + if (is_rtc_hctosys(rtc)) + remove_proc_entry("driver/rtc", NULL); +} -- cgit v1.3.1