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/ibmasm/lowlevel.c | 75 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 drivers/misc/ibmasm/lowlevel.c (limited to 'drivers/misc/ibmasm/lowlevel.c') diff --git a/drivers/misc/ibmasm/lowlevel.c b/drivers/misc/ibmasm/lowlevel.c new file mode 100644 index 000000000..5313230f3 --- /dev/null +++ b/drivers/misc/ibmasm/lowlevel.c @@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * IBM ASM Service Processor Device Driver + * + * Copyright (C) IBM Corporation, 2004 + * + * Author: Max Asböck + */ + +#include "ibmasm.h" +#include "lowlevel.h" +#include "i2o.h" +#include "dot_command.h" +#include "remote.h" + +static struct i2o_header header = I2O_HEADER_TEMPLATE; + + +int ibmasm_send_i2o_message(struct service_processor *sp) +{ + u32 mfa; + size_t command_size; + struct i2o_message *message; + struct command *command = sp->current_command; + + command_size = get_dot_command_size(command->buffer); + if (command_size > command->buffer_size) + return 1; + if (command_size > I2O_COMMAND_SIZE) + command_size = I2O_COMMAND_SIZE; + + mfa = get_mfa_inbound(sp->base_address); + if (!mfa) + return 1; + + header.message_size = outgoing_message_size((unsigned int)command_size); + message = get_i2o_message(sp->base_address, mfa); + + memcpy_toio(&message->header, &header, sizeof(struct i2o_header)); + memcpy_toio(&message->data, command->buffer, command_size); + + set_mfa_inbound(sp->base_address, mfa); + + return 0; +} + +irqreturn_t ibmasm_interrupt_handler(int irq, void * dev_id) +{ + u32 mfa; + struct service_processor *sp = (struct service_processor *)dev_id; + void __iomem *base_address = sp->base_address; + char tsbuf[32]; + + if (!sp_interrupt_pending(base_address)) + return IRQ_NONE; + + dbg("respond to interrupt at %s\n", get_timestamp(tsbuf)); + + if (mouse_interrupt_pending(sp)) { + ibmasm_handle_mouse_interrupt(sp); + clear_mouse_interrupt(sp); + } + + mfa = get_mfa_outbound(base_address); + if (valid_mfa(mfa)) { + struct i2o_message *msg = get_i2o_message(base_address, mfa); + ibmasm_receive_message(sp, &msg->data, incoming_data_size(msg)); + } else + dbg("didn't get a valid MFA\n"); + + set_mfa_outbound(base_address, mfa); + dbg("finished interrupt at %s\n", get_timestamp(tsbuf)); + + return IRQ_HANDLED; +} -- cgit v1.3.1