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, 28 insertions, 0 deletions

diff --git a/scripts/Makefile.autofdo b/scripts/Makefile.autofdo
new file mode 100644
index 000000000..1442043da
--- /dev/null
+++ b/scripts/Makefile.autofdo
@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-2.0
+
+# Enable available and selected Clang AutoFDO features.
+
+CFLAGS_AUTOFDO_CLANG := -fdebug-info-for-profiling -mllvm -enable-fs-discriminator=true -mllvm -improved-fs-discriminator=true
+RUSTFLAGS_AUTOFDO_CLANG := $(if $(call rustc-min-version,109800),-Zdebuginfo-for-profiling,-Zdebug-info-for-profiling) -Cllvm-args=-enable-fs-discriminator=true -Cllvm-args=-improved-fs-discriminator=true
+
+ifndef CONFIG_DEBUG_INFO
+  CFLAGS_AUTOFDO_CLANG += -gmlt
+  RUSTFLAGS_AUTOFDO_CLANG += -Cdebuginfo=line-tables-only
+endif
+
+ifdef CLANG_AUTOFDO_PROFILE
+  CFLAGS_AUTOFDO_CLANG += -fprofile-sample-use=$(CLANG_AUTOFDO_PROFILE) -ffunction-sections
+  CFLAGS_AUTOFDO_CLANG += -fsplit-machine-functions
+  RUSTFLAGS_AUTOFDO_CLANG += -Zprofile-sample-use=$(CLANG_AUTOFDO_PROFILE) -Zfunction-sections=y
+  RUSTFLAGS_AUTOFDO_CLANG += -Cllvm-args=-split-machine-functions
+endif
+
+ifdef CONFIG_LTO_CLANG_THIN
+  ifdef CLANG_AUTOFDO_PROFILE
+    KBUILD_LDFLAGS += --lto-sample-profile=$(CLANG_AUTOFDO_PROFILE)
+  endif
+  KBUILD_LDFLAGS += --mllvm=-enable-fs-discriminator=true --mllvm=-improved-fs-discriminator=true -plugin-opt=thinlto
+  KBUILD_LDFLAGS += -plugin-opt=-split-machine-functions
+endif
+
+export CFLAGS_AUTOFDO_CLANG RUSTFLAGS_AUTOFDO_CLANG