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, 29 insertions, 0 deletions

diff --git a/include/rdma/ib_ucaps.h b/include/rdma/ib_ucaps.h
new file mode 100644
index 000000000..b629c9911
--- /dev/null
+++ b/include/rdma/ib_ucaps.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/*
+ * Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved
+ */
+
+#ifndef _IB_UCAPS_H_
+#define _IB_UCAPS_H_
+
+#define UCAP_ENABLED(ucaps, type) (!!((ucaps) & (1U << (type))))
+
+enum rdma_user_cap {
+	RDMA_UCAP_MLX5_CTRL_LOCAL,
+	RDMA_UCAP_MLX5_CTRL_OTHER_VHCA,
+	RDMA_UCAP_MAX
+};
+
+int ib_get_ucaps(int *fds, int fd_count, uint64_t *idx_mask);
+#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
+int ib_create_ucap(enum rdma_user_cap type);
+void ib_remove_ucap(enum rdma_user_cap type);
+#else
+static inline int ib_create_ucap(enum rdma_user_cap type)
+{
+	return -EOPNOTSUPP;
+}
+static inline void ib_remove_ucap(enum rdma_user_cap type) {}
+#endif /* CONFIG_INFINIBAND_USER_ACCESS */
+
+#endif /* _IB_UCAPS_H_ */