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, 47 insertions, 0 deletions

diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh
new file mode 100755
index 000000000..031f2192b
--- /dev/null
+++ b/scripts/min-tool-version.sh
@@ -0,0 +1,47 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Print the minimum supported version of the given tool.
+# When you raise the minimum version, please update
+# Documentation/process/changes.rst as well.
+
+set -e
+
+if [ $# != 1 ]; then
+	echo "Usage: $0 toolname" >&2
+	exit 1
+fi
+
+case "$1" in
+binutils)
+	echo 2.30.0
+	;;
+gcc)
+	if [ "$ARCH" = parisc64 ]; then
+		echo 12.0.0
+	else
+		echo 8.1.0
+	fi
+	;;
+llvm)
+	if [ "$SRCARCH" = loongarch ]; then
+		echo 18.0.0
+	else
+		echo 17.0.1
+	fi
+	;;
+rustc)
+	if [ "$SRCARCH" = "s390" ]; then
+		echo 1.96.0
+	else
+		echo 1.85.0
+	fi
+	;;
+bindgen)
+	echo 0.71.1
+	;;
+*)
+	echo "$1: unknown tool" >&2
+	exit 1
+	;;
+esac