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 --- arch/powerpc/boot/ebony.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 arch/powerpc/boot/ebony.c (limited to 'arch/powerpc/boot/ebony.c') diff --git a/arch/powerpc/boot/ebony.c b/arch/powerpc/boot/ebony.c new file mode 100644 index 000000000..add2316d3 --- /dev/null +++ b/arch/powerpc/boot/ebony.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 2007 David Gibson, IBM Corporation. + * + * Based on earlier code: + * Copyright (C) Paul Mackerras 1997. + * + * Matt Porter + * Copyright 2002-2005 MontaVista Software Inc. + * + * Eugene Surovegin or + * Copyright (c) 2003, 2004 Zultys Technologies + */ +#include +#include +#include "types.h" +#include "elf.h" +#include "string.h" +#include "stdio.h" +#include "page.h" +#include "ops.h" +#include "reg.h" +#include "io.h" +#include "dcr.h" +#include "4xx.h" +#include "44x.h" + +static u8 *ebony_mac0, *ebony_mac1; + +#define EBONY_FPGA_PATH "/plb/opb/ebc/fpga" +#define EBONY_FPGA_FLASH_SEL 0x01 +#define EBONY_SMALL_FLASH_PATH "/plb/opb/ebc/small-flash" + +static void ebony_flashsel_fixup(void) +{ + void *devp; + u32 reg[3] = {0x0, 0x0, 0x80000}; + u8 *fpga; + u8 fpga_reg0 = 0x0; + + devp = finddevice(EBONY_FPGA_PATH); + if (!devp) + fatal("Couldn't locate FPGA node %s\n\r", EBONY_FPGA_PATH); + + if (getprop(devp, "virtual-reg", &fpga, sizeof(fpga)) != sizeof(fpga)) + fatal("%s has missing or invalid virtual-reg property\n\r", + EBONY_FPGA_PATH); + + fpga_reg0 = in_8(fpga); + + devp = finddevice(EBONY_SMALL_FLASH_PATH); + if (!devp) + fatal("Couldn't locate small flash node %s\n\r", + EBONY_SMALL_FLASH_PATH); + + if (getprop(devp, "reg", reg, sizeof(reg)) != sizeof(reg)) + fatal("%s has reg property of unexpected size\n\r", + EBONY_SMALL_FLASH_PATH); + + /* Invert address bit 14 (IBM-endian) if FLASH_SEL fpga bit is set */ + if (fpga_reg0 & EBONY_FPGA_FLASH_SEL) + reg[1] ^= 0x80000; + + setprop(devp, "reg", reg, sizeof(reg)); +} + +static void ebony_fixups(void) +{ + // FIXME: sysclk should be derived by reading the FPGA registers + unsigned long sysclk = 33000000; + + ibm440gp_fixup_clocks(sysclk, 6 * 1843200); + ibm4xx_sdram_fixup_memsize(); + dt_fixup_mac_address_by_alias("ethernet0", ebony_mac0); + dt_fixup_mac_address_by_alias("ethernet1", ebony_mac1); + ibm4xx_fixup_ebc_ranges("/plb/opb/ebc"); + ebony_flashsel_fixup(); +} + +void ebony_init(void *mac0, void *mac1) +{ + platform_ops.fixups = ebony_fixups; + platform_ops.exit = ibm44x_dbcr_reset; + ebony_mac0 = mac0; + ebony_mac1 = mac1; + fdt_init(_dtb_start); + serial_console_init(); +} -- cgit v1.3.1