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, 124 insertions, 0 deletions

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
new file mode 100644
index 000000000..5b713837e
--- /dev/null
+++ b/tools/perf/Makefile
@@ -0,0 +1,124 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# This is a simple wrapper Makefile that calls the main Makefile.perf
+# with a -j option to do parallel builds
+#
+# If you want to invoke the perf build in some non-standard way then
+# you can use the 'make -f Makefile.perf' method to invoke it.
+#
+
+#
+# Clear out the built-in rules GNU make defines by default (such as .o targets),
+# so that we pass through all targets to Makefile.perf:
+#
+.SUFFIXES:
+
+#
+# We don't want to pass along options like -j:
+#
+unexport MAKEFLAGS
+
+#
+# Do a parallel build with multiple jobs, based on the number of CPUs online
+# in this system: 'make -j8' on a 8-CPU system, etc.
+#
+# (To override it, run 'make JOBS=1' and similar.)
+#
+ifeq ($(JOBS),)
+  JOBS := $(shell (getconf _NPROCESSORS_ONLN || grep -E -c '^processor|^CPU[0-9]' /proc/cpuinfo) 2>/dev/null)
+  ifeq ($(JOBS),0)
+    JOBS := 1
+  endif
+endif
+
+#
+# Only pass canonical directory names as the output directory:
+#
+ifneq ($(O),)
+  FULL_O := $(shell cd $(PWD); readlink -f $(O) || echo $(O))
+endif
+
+#
+# Only accept the 'DEBUG' variable from the command line:
+#
+ifeq ("$(origin DEBUG)", "command line")
+  ifeq ($(DEBUG),)
+    override DEBUG = 0
+  else
+    SET_DEBUG = "DEBUG=$(DEBUG)"
+  endif
+else
+  override DEBUG = 0
+endif
+
+ifeq ($(JOBS),1)
+  BUILD_TYPE := sequential
+else
+  BUILD_TYPE := parallel
+endif
+
+define print_msg
+  @printf '  BUILD:   Doing '\''make \033[33m-j'$(JOBS)'\033[m'\'' $(BUILD_TYPE) build\n'
+endef
+
+define make
+  @$(MAKE) -f Makefile.perf --no-print-directory -j$(JOBS) O=$(FULL_O) $(SET_DEBUG) $@
+endef
+
+#
+# Needed if no target specified:
+# (Except for tags and TAGS targets. The reason is that the
+# Makefile does not treat tags/TAGS as targets but as files
+# and thus won't rebuilt them once they are in place.)
+#
+all tags TAGS:
+	$(print_msg)
+	$(make)
+
+ifdef MAKECMDGOALS
+has_clean := 0
+ifneq ($(filter clean,$(MAKECMDGOALS)),)
+  has_clean := 1
+endif # clean
+
+ifeq ($(has_clean),1)
+  rest := $(filter-out clean,$(MAKECMDGOALS))
+  ifneq ($(rest),)
+$(rest): clean
+  endif # rest
+endif # has_clean
+endif # MAKECMDGOALS
+
+#
+# Explicitly disable parallelism for the clean target.
+#
+clean:
+	$(make) -j1
+
+#
+# The build-test target is not really parallel, don't print the jobs info,
+# it also uses only the tests/make targets that don't pollute the source
+# repository, i.e. that uses O= or builds the tarpkg outside the source
+# repo directories.
+#
+# For a full test, use:
+#
+# make -C tools/perf -f tests/make
+#
+build-test:
+	@$(MAKE) SHUF=1 -f tests/make REUSE_FEATURES_DUMP=1 MK=Makefile SET_PARALLEL=1 --no-print-directory tarpkg make_static make_with_gtk2 out
+
+build-test-tarball:
+	@$(MAKE) -f tests/make REUSE_FEATURES_DUMP=1 MK=Makefile SET_PARALLEL=1 --no-print-directory out
+
+check-headers:
+	@./check-headers.sh
+
+#
+# All other targets get passed through:
+#
+%: FORCE
+	$(print_msg)
+	$(make)
+
+.PHONY: tags TAGS FORCE Makefile build-test build-test-tarball check-headers