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/mips/power/cpu.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 arch/mips/power/cpu.c (limited to 'arch/mips/power/cpu.c') diff --git a/arch/mips/power/cpu.c b/arch/mips/power/cpu.c new file mode 100644 index 000000000..d8ef7778e --- /dev/null +++ b/arch/mips/power/cpu.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Suspend support specific for mips. + * + * Copyright (C) 2009 Lemote Inc. + * Author: Hu Hongbing + * Wu Zhangjin + */ +#include +#include +#include +#include + +static u32 saved_status; +struct pt_regs saved_regs; + +void save_processor_state(void) +{ + saved_status = read_c0_status(); + + if (is_fpu_owner()) + save_fp(current); + + save_dsp(current); +} + +void restore_processor_state(void) +{ + write_c0_status(saved_status); + + if (is_fpu_owner()) + restore_fp(current); + + restore_dsp(current); +} + +int pfn_is_nosave(unsigned long pfn) +{ + unsigned long nosave_begin_pfn = PFN_DOWN(__pa(&__nosave_begin)); + unsigned long nosave_end_pfn = PFN_UP(__pa(&__nosave_end)); + + return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn); +} -- cgit v1.3.1