openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

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 <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 143 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
new file mode 100644
index 000000000..4bd9d1230
--- /dev/null
+++ b/arch/powerpc/kvm/Makefile
@@ -0,0 +1,143 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for Kernel-based Virtual Machine module
+#
+
+ccflags-y := -Ivirt/kvm -Iarch/powerpc/kvm
+
+include $(srctree)/virt/kvm/Makefile.kvm
+
+common-objs-y += powerpc.o emulate_loadstore.o
+obj-$(CONFIG_KVM_EXIT_TIMING) += timing.o
+obj-$(CONFIG_KVM_BOOK3S_HANDLER) += book3s_exports.o
+
+AFLAGS_booke_interrupts.o := -I$(objtree)/$(obj)
+
+kvm-e500-objs := \
+	$(common-objs-y) \
+	emulate.o \
+	booke.o \
+	booke_emulate.o \
+	booke_interrupts.o \
+	e500.o \
+	e500_mmu.o \
+	e500_mmu_host.o \
+	e500_emulate.o
+kvm-objs-$(CONFIG_KVM_E500V2) := $(kvm-e500-objs)
+
+kvm-e500mc-objs := \
+	$(common-objs-y) \
+	emulate.o \
+	booke.o \
+	booke_emulate.o \
+	bookehv_interrupts.o \
+	e500mc.o \
+	e500_mmu.o \
+	e500_mmu_host.o \
+	e500_emulate.o
+kvm-objs-$(CONFIG_KVM_E500MC) := $(kvm-e500mc-objs)
+
+kvm-pr-y := \
+	fpu.o \
+	emulate.o \
+	book3s_paired_singles.o \
+	book3s_pr.o \
+	book3s_pr_papr.o \
+	book3s_emulate.o \
+	book3s_interrupts.o \
+	book3s_mmu_hpte.o \
+	book3s_64_mmu_host.o \
+	book3s_64_mmu.o \
+	book3s_32_mmu.o
+
+kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HANDLER) += \
+	book3s_64_entry.o \
+	tm.o
+
+ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
+kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HANDLER) += \
+	book3s_rmhandlers.o
+endif
+
+kvm-hv-y += \
+	book3s_hv.o \
+	book3s_hv_interrupts.o \
+	book3s_64_mmu_hv.o \
+	book3s_64_mmu_radix.o \
+	book3s_hv_nested.o
+
+kvm-hv-$(CONFIG_PPC_UV) += \
+	book3s_hv_uvmem.o
+
+kvm-hv-$(CONFIG_PPC_TRANSACTIONAL_MEM) += \
+	book3s_hv_tm.o
+
+kvm-book3s_64-builtin-xics-objs-$(CONFIG_KVM_XICS) := \
+	book3s_hv_rm_xics.o
+
+kvm-book3s_64-builtin-tm-objs-$(CONFIG_PPC_TRANSACTIONAL_MEM) += \
+	book3s_hv_tm_builtin.o
+
+ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HANDLER) += \
+	book3s_hv_hmi.o \
+	book3s_hv_p9_entry.o \
+	book3s_hv_rmhandlers.o \
+	book3s_hv_rm_mmu.o \
+	book3s_hv_ras.o \
+	book3s_hv_builtin.o \
+	book3s_hv_p9_perf.o \
+	book3s_hv_nestedv2.o \
+	guest-state-buffer.o \
+	$(kvm-book3s_64-builtin-tm-objs-y) \
+	$(kvm-book3s_64-builtin-xics-objs-y)
+
+obj-$(CONFIG_GUEST_STATE_BUFFER_TEST) += test-guest-state-buffer.o
+endif
+
+kvm-book3s_64-objs-$(CONFIG_KVM_XICS) += \
+	book3s_xics.o
+
+kvm-book3s_64-objs-$(CONFIG_KVM_XIVE) += book3s_xive.o book3s_xive_native.o
+kvm-book3s_64-objs-$(CONFIG_SPAPR_TCE_IOMMU) += book3s_64_vio.o
+
+kvm-book3s_64-module-objs := \
+	$(common-objs-y) \
+	book3s.o \
+	book3s_rtas.o \
+	$(kvm-book3s_64-objs-y)
+
+kvm-objs-$(CONFIG_KVM_BOOK3S_64) := $(kvm-book3s_64-module-objs)
+
+kvm-book3s_32-objs := \
+	$(common-objs-y) \
+	emulate.o \
+	fpu.o \
+	book3s_paired_singles.o \
+	book3s.o \
+	book3s_pr.o \
+	book3s_emulate.o \
+	book3s_interrupts.o \
+	book3s_mmu_hpte.o \
+	book3s_32_mmu_host.o \
+	book3s_32_mmu.o
+kvm-objs-$(CONFIG_KVM_BOOK3S_32) := $(kvm-book3s_32-objs)
+
+kvm-objs-$(CONFIG_KVM_MPIC) += mpic.o
+
+kvm-y += $(kvm-objs-m) $(kvm-objs-y)
+
+obj-$(CONFIG_KVM_E500V2) += kvm.o
+obj-$(CONFIG_KVM_E500MC) += kvm.o
+obj-$(CONFIG_KVM_BOOK3S_64) += kvm.o
+obj-$(CONFIG_KVM_BOOK3S_32) += kvm.o
+
+obj-$(CONFIG_KVM_BOOK3S_64_PR) += kvm-pr.o
+obj-$(CONFIG_KVM_BOOK3S_64_HV) += kvm-hv.o
+
+obj-y += $(kvm-book3s_64-builtin-objs-y)
+
+# KVM does a lot in real-mode, and 64-bit Book3S KASAN doesn't support that
+ifdef CONFIG_PPC_BOOK3S_64
+KASAN_SANITIZE := n
+endif