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/clocksource/timer-versatile.c | 40 +++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 drivers/clocksource/timer-versatile.c (limited to 'drivers/clocksource/timer-versatile.c') diff --git a/drivers/clocksource/timer-versatile.c b/drivers/clocksource/timer-versatile.c new file mode 100644 index 000000000..f5d017b31 --- /dev/null +++ b/drivers/clocksource/timer-versatile.c @@ -0,0 +1,40 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * Copyright (C) 2014 ARM Limited + */ + +#include +#include +#include +#include +#include + +#define SYS_24MHZ 0x05c + +static void __iomem *versatile_sys_24mhz; + +static u64 notrace versatile_sys_24mhz_read(void) +{ + return readl(versatile_sys_24mhz); +} + +static int __init versatile_sched_clock_init(struct device_node *node) +{ + void __iomem *base = of_iomap(node, 0); + + of_node_clear_flag(node, OF_POPULATED); + + if (!base) + return -ENXIO; + + versatile_sys_24mhz = base + SYS_24MHZ; + + sched_clock_register(versatile_sys_24mhz_read, 32, 24000000); + + return 0; +} +TIMER_OF_DECLARE(vexpress, "arm,vexpress-sysreg", + versatile_sched_clock_init); +TIMER_OF_DECLARE(versatile, "arm,versatile-sysreg", + versatile_sched_clock_init); -- cgit v1.3.1