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, 34 insertions, 0 deletions

diff --git a/tools/testing/kunit/kunit-completion.sh b/tools/testing/kunit/kunit-completion.sh
new file mode 100644
index 000000000..f053e7b5d
--- /dev/null
+++ b/tools/testing/kunit/kunit-completion.sh
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: GPL-2.0
+# bash completion support for KUnit
+
+_kunit_dir=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+
+_kunit()
+{
+	local cur prev words cword
+	_init_completion || return
+
+	local script="${_kunit_dir}/kunit.py"
+
+	if [[ $cword -eq 1 && "$cur" != -* ]]; then
+		local cmds=$(${script} --list-cmds 2>/dev/null)
+		COMPREPLY=($(compgen -W "${cmds}" -- "$cur"))
+		return 0
+	fi
+
+	if [[ "$cur" == -* ]]; then
+		if [[ -n "${words[1]}" && "${words[1]}" != -* ]]; then
+			local opts=$(${script} ${words[1]} --list-opts 2>/dev/null)
+			COMPREPLY=($(compgen -W "${opts}" -- "$cur"))
+			return 0
+		else
+			local opts=$(${script} --list-opts 2>/dev/null)
+			COMPREPLY=($(compgen -W "${opts}" -- "$cur"))
+			return 0
+		fi
+	fi
+}
+
+complete -o default -F _kunit kunit.py
+complete -o default -F _kunit kunit
+complete -o default -F _kunit ./tools/testing/kunit/kunit.py