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/kvm/stats.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 arch/mips/kvm/stats.c (limited to 'arch/mips/kvm/stats.c') diff --git a/arch/mips/kvm/stats.c b/arch/mips/kvm/stats.c new file mode 100644 index 000000000..3e6682018 --- /dev/null +++ b/arch/mips/kvm/stats.c @@ -0,0 +1,63 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * KVM/MIPS: COP0 access histogram + * + * Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved. + * Authors: Sanjay Lal + */ + +#include + +char *kvm_cop0_str[N_MIPS_COPROC_REGS] = { + "Index", + "Random", + "EntryLo0", + "EntryLo1", + "Context", + "PG Mask", + "Wired", + "HWREna", + "BadVAddr", + "Count", + "EntryHI", + "Compare", + "Status", + "Cause", + "EXC PC", + "PRID", + "Config", + "LLAddr", + "Watch Lo", + "Watch Hi", + "X Context", + "Reserved", + "Impl Dep", + "Debug", + "DEPC", + "PerfCnt", + "ErrCtl", + "CacheErr", + "TagLo", + "TagHi", + "ErrorEPC", + "DESAVE" +}; + +void kvm_mips_dump_stats(struct kvm_vcpu *vcpu) +{ +#ifdef CONFIG_KVM_MIPS_DEBUG_COP0_COUNTERS + int i, j; + + kvm_info("\nKVM VCPU[%d] COP0 Access Profile:\n", vcpu->vcpu_id); + for (i = 0; i < N_MIPS_COPROC_REGS; i++) { + for (j = 0; j < N_MIPS_COPROC_SEL; j++) { + if (vcpu->arch.cop0.stat[i][j]) + kvm_info("%s[%d]: %lu\n", kvm_cop0_str[i], j, + vcpu->arch.cop0.stat[i][j]); + } + } +#endif +} -- cgit v1.3.1