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, 73 insertions, 0 deletions

diff --git a/fs/smb/server/stats.h b/fs/smb/server/stats.h
new file mode 100644
index 000000000..b60c30c69
--- /dev/null
+++ b/fs/smb/server/stats.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2025, LG Electronics.
+ *   Author(s): Hyunchul Lee <hyc.lee@gmail.com>
+ *   Copyright (C) 2025, Samsung Electronics.
+ *   Author(s): Vedansh Bhardwaj <v.bhardwaj@samsung.com>
+ */
+
+#ifndef __KSMBD_STATS_H__
+#define __KSMBD_STATS_H__
+
+#define KSMBD_COUNTER_MAX_REQS	19
+
+enum {
+	KSMBD_COUNTER_SESSIONS = 0,
+	KSMBD_COUNTER_TREE_CONNS,
+	KSMBD_COUNTER_REQUESTS,
+	KSMBD_COUNTER_READ_BYTES,
+	KSMBD_COUNTER_WRITE_BYTES,
+	KSMBD_COUNTER_FIRST_REQ,
+	KSMBD_COUNTER_LAST_REQ = KSMBD_COUNTER_FIRST_REQ +
+				KSMBD_COUNTER_MAX_REQS - 1,
+	KSMBD_COUNTER_MAX,
+};
+
+#ifdef CONFIG_PROC_FS
+extern struct ksmbd_counters ksmbd_counters;
+
+struct ksmbd_counters {
+	struct percpu_counter	counters[KSMBD_COUNTER_MAX];
+};
+
+static inline void ksmbd_counter_inc(int type)
+{
+	percpu_counter_inc(&ksmbd_counters.counters[type]);
+}
+
+static inline void ksmbd_counter_dec(int type)
+{
+	percpu_counter_dec(&ksmbd_counters.counters[type]);
+}
+
+static inline void ksmbd_counter_add(int type, s64 value)
+{
+	percpu_counter_add(&ksmbd_counters.counters[type], value);
+}
+
+static inline void ksmbd_counter_sub(int type, s64 value)
+{
+	percpu_counter_sub(&ksmbd_counters.counters[type], value);
+}
+
+static inline void ksmbd_counter_inc_reqs(unsigned int cmd)
+{
+	if (cmd < KSMBD_COUNTER_MAX_REQS)
+		percpu_counter_inc(&ksmbd_counters.counters[KSMBD_COUNTER_FIRST_REQ + cmd]);
+}
+
+static inline s64 ksmbd_counter_sum(int type)
+{
+	return percpu_counter_sum_positive(&ksmbd_counters.counters[type]);
+}
+#else
+
+static inline void ksmbd_counter_inc(int type) {}
+static inline void ksmbd_counter_dec(int type) {}
+static inline void ksmbd_counter_add(int type, s64 value) {}
+static inline void ksmbd_counter_sub(int type, s64 value) {}
+static inline void ksmbd_counter_inc_reqs(unsigned int cmd) {}
+static inline s64 ksmbd_counter_sum(int type) { return 0; }
+#endif
+
+#endif