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/misc/dummy-irq.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 drivers/misc/dummy-irq.c (limited to 'drivers/misc/dummy-irq.c') diff --git a/drivers/misc/dummy-irq.c b/drivers/misc/dummy-irq.c new file mode 100644 index 000000000..fe3bfcb31 --- /dev/null +++ b/drivers/misc/dummy-irq.c @@ -0,0 +1,60 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Dummy IRQ handler driver. + * + * This module only registers itself as a handler that is specified to it + * by the 'irq' parameter. + * + * The sole purpose of this module is to help with debugging of systems on + * which spurious IRQs would happen on disabled IRQ vector. + * + * Copyright (C) 2013 Jiri Kosina + */ + +#include +#include +#include + +static int irq = -1; + +static irqreturn_t dummy_interrupt(int irq, void *dev_id) +{ + static int count = 0; + + if (count == 0) { + printk(KERN_INFO "dummy-irq: interrupt occurred on IRQ %d\n", + irq); + count++; + } + + return IRQ_NONE; +} + +static int __init dummy_irq_init(void) +{ + if (irq < 0) { + printk(KERN_ERR "dummy-irq: no IRQ given. Use irq=N\n"); + return -EIO; + } + if (request_irq(irq, &dummy_interrupt, IRQF_SHARED, "dummy_irq", &irq)) { + printk(KERN_ERR "dummy-irq: cannot register IRQ %d\n", irq); + return -EIO; + } + printk(KERN_INFO "dummy-irq: registered for IRQ %d\n", irq); + return 0; +} + +static void __exit dummy_irq_exit(void) +{ + printk(KERN_INFO "dummy-irq unloaded\n"); + free_irq(irq, &irq); +} + +module_init(dummy_irq_init); +module_exit(dummy_irq_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Jiri Kosina"); +module_param_hw(irq, uint, irq, 0444); +MODULE_PARM_DESC(irq, "The IRQ to register for"); +MODULE_DESCRIPTION("Dummy IRQ handler driver"); -- cgit v1.3.1