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/firmware/efi/riscv-runtime.c | 159 +++++++++++++++++++++++++++++++++++ 1 file changed, 159 insertions(+) create mode 100644 drivers/firmware/efi/riscv-runtime.c (limited to 'drivers/firmware/efi/riscv-runtime.c') diff --git a/drivers/firmware/efi/riscv-runtime.c b/drivers/firmware/efi/riscv-runtime.c new file mode 100644 index 000000000..60cdf7bf1 --- /dev/null +++ b/drivers/firmware/efi/riscv-runtime.c @@ -0,0 +1,159 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Extensible Firmware Interface + * + * Copyright (C) 2020 Western Digital Corporation or its affiliates. + * + * Based on Extensible Firmware Interface Specification version 2.4 + * Adapted from drivers/firmware/efi/arm-runtime.c + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +static bool __init efi_virtmap_init(void) +{ + efi_memory_desc_t *md; + + efi_mm.pgd = pgd_alloc(&efi_mm); + mm_init_cpumask(&efi_mm); + init_new_context(NULL, &efi_mm); + + for_each_efi_memory_desc(md) { + if (!(md->attribute & EFI_MEMORY_RUNTIME)) + continue; + if (md->virt_addr == U64_MAX) + return false; + + efi_create_mapping(&efi_mm, md); + } + + if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions)) + return false; + + return true; +} + +/* + * Enable the UEFI Runtime Services if all prerequisites are in place, i.e., + * non-early mapping of the UEFI system table and virtual mappings for all + * EFI_MEMORY_RUNTIME regions. + */ +static int __init riscv_enable_runtime_services(void) +{ + u64 mapsize; + + if (!efi_enabled(EFI_BOOT)) { + pr_info("EFI services will not be available.\n"); + return 0; + } + + efi_memmap_unmap(); + + mapsize = efi.memmap.desc_size * efi.memmap.nr_map; + + if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) { + pr_err("Failed to remap EFI memory map\n"); + return 0; + } + + if (efi_soft_reserve_enabled()) { + efi_memory_desc_t *md; + + for_each_efi_memory_desc(md) { + u64 md_size = md->num_pages << EFI_PAGE_SHIFT; + struct resource *res; + + if (!(md->attribute & EFI_MEMORY_SP)) + continue; + + res = kzalloc_obj(*res); + if (WARN_ON(!res)) + break; + + res->start = md->phys_addr; + res->end = md->phys_addr + md_size - 1; + res->name = "Soft Reserved"; + res->flags = IORESOURCE_MEM; + res->desc = IORES_DESC_SOFT_RESERVED; + + insert_resource(&iomem_resource, res); + } + } + + if (efi_runtime_disabled()) { + pr_info("EFI runtime services will be disabled.\n"); + return 0; + } + + if (efi_enabled(EFI_RUNTIME_SERVICES)) { + pr_info("EFI runtime services access via paravirt.\n"); + return 0; + } + + pr_info("Remapping and enabling EFI services.\n"); + + if (!efi_virtmap_init()) { + pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n"); + return -ENOMEM; + } + + /* Set up runtime services function pointers */ + efi_native_runtime_setup(); + set_bit(EFI_RUNTIME_SERVICES, &efi.flags); + + return 0; +} +early_initcall(riscv_enable_runtime_services); + +static void efi_virtmap_load(void) +{ + preempt_disable(); + switch_mm(current->active_mm, &efi_mm, NULL); +} + +static void efi_virtmap_unload(void) +{ + switch_mm(&efi_mm, current->active_mm, NULL); + preempt_enable(); +} + +void arch_efi_call_virt_setup(void) +{ + sync_kernel_mappings(efi_mm.pgd); + efi_virtmap_load(); +} + +void arch_efi_call_virt_teardown(void) +{ + efi_virtmap_unload(); +} + +static int __init riscv_dmi_init(void) +{ + /* + * On riscv, DMI depends on UEFI, and dmi_setup() needs to + * be called early because dmi_id_init(), which is an arch_initcall + * itself, depends on dmi_scan_machine() having been called already. + */ + dmi_setup(); + + return 0; +} +core_initcall(riscv_dmi_init); -- cgit v1.3.1