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, 26 insertions, 0 deletions

diff --git a/arch/powerpc/perf/Makefile b/arch/powerpc/perf/Makefile
new file mode 100644
index 000000000..78dd7e252
--- /dev/null
+++ b/arch/powerpc/perf/Makefile
@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-y				+= callchain.o callchain_$(BITS).o perf_regs.o
+obj-$(CONFIG_COMPAT)		+= callchain_32.o
+
+obj-$(CONFIG_PPC_PERF_CTRS)	+= core-book3s.o
+obj64-$(CONFIG_PPC_PERF_CTRS)	+= ppc970-pmu.o power5-pmu.o \
+				   power5+-pmu.o power6-pmu.o power7-pmu.o \
+				   isa207-common.o power8-pmu.o power9-pmu.o \
+				   generic-compat-pmu.o power10-pmu.o bhrb.o
+obj32-$(CONFIG_PPC_PERF_CTRS)	+= mpc7450-pmu.o
+
+obj-$(CONFIG_PPC_POWERNV)	+= imc-pmu.o
+obj-$(CONFIG_FSL_EMB_PERF_EVENT) += core-fsl-emb.o
+obj-$(CONFIG_FSL_EMB_PERF_EVENT_E500) += e500-pmu.o e6500-pmu.o
+
+obj-$(CONFIG_HV_PERF_CTRS) += hv-24x7.o hv-gpci.o hv-common.o vpa-dtl.o
+
+obj-$(CONFIG_VPA_PMU) += vpa-pmu.o
+
+obj-$(CONFIG_KVM_BOOK3S_HV_PMU) += kvm-hv-pmu.o
+
+obj-$(CONFIG_PPC_8xx) += 8xx-pmu.o
+
+obj-$(CONFIG_PPC64)		+= $(obj64-y)
+obj-$(CONFIG_PPC32)		+= $(obj32-y)