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/lib/pmem.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 arch/powerpc/lib/pmem.c (limited to 'arch/powerpc/lib/pmem.c') diff --git a/arch/powerpc/lib/pmem.c b/arch/powerpc/lib/pmem.c new file mode 100644 index 000000000..0f0f2d851 --- /dev/null +++ b/arch/powerpc/lib/pmem.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright(c) 2017 IBM Corporation. All rights reserved. + */ + +#include +#include +#include +#include + +#include + +static inline void __clean_pmem_range(unsigned long start, unsigned long stop) +{ + unsigned long shift = l1_dcache_shift(); + unsigned long bytes = l1_dcache_bytes(); + void *addr = (void *)(start & ~(bytes - 1)); + unsigned long size = stop - (unsigned long)addr + (bytes - 1); + unsigned long i; + + for (i = 0; i < size >> shift; i++, addr += bytes) + asm volatile(PPC_DCBSTPS(%0, %1): :"i"(0), "r"(addr): "memory"); +} + +static inline void __flush_pmem_range(unsigned long start, unsigned long stop) +{ + unsigned long shift = l1_dcache_shift(); + unsigned long bytes = l1_dcache_bytes(); + void *addr = (void *)(start & ~(bytes - 1)); + unsigned long size = stop - (unsigned long)addr + (bytes - 1); + unsigned long i; + + for (i = 0; i < size >> shift; i++, addr += bytes) + asm volatile(PPC_DCBFPS(%0, %1): :"i"(0), "r"(addr): "memory"); +} + +static inline void clean_pmem_range(unsigned long start, unsigned long stop) +{ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + return __clean_pmem_range(start, stop); +} + +static inline void flush_pmem_range(unsigned long start, unsigned long stop) +{ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + return __flush_pmem_range(start, stop); +} + +/* + * CONFIG_ARCH_HAS_PMEM_API symbols + */ +void arch_wb_cache_pmem(void *addr, size_t size) +{ + unsigned long start = (unsigned long) addr; + clean_pmem_range(start, start + size); +} +EXPORT_SYMBOL_GPL(arch_wb_cache_pmem); + +void arch_invalidate_pmem(void *addr, size_t size) +{ + unsigned long start = (unsigned long) addr; + flush_pmem_range(start, start + size); +} +EXPORT_SYMBOL_GPL(arch_invalidate_pmem); + +/* + * CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE symbols + */ +size_t copy_from_user_flushcache(void *dest, const void __user *src, + size_t size) +{ + unsigned long not_copied, start = (unsigned long) dest; + + src = mask_user_address(src); + not_copied = __copy_from_user(dest, src, size); + clean_pmem_range(start, start + size); + + return not_copied; +} + +void memcpy_flushcache(void *dest, const void *src, size_t size) +{ + unsigned long start = (unsigned long) dest; + + memcpy(dest, src, size); + clean_pmem_range(start, start + size); +} +EXPORT_SYMBOL(memcpy_flushcache); -- cgit v1.3.1