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, 89 insertions, 0 deletions

diff --git a/crypto/sm3.c b/crypto/sm3.c
new file mode 100644
index 000000000..05111a99b
--- /dev/null
+++ b/crypto/sm3.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SM3 secure hash, as specified by OSCCA GM/T 0004-2012 SM3 and
+ * described at https://tools.ietf.org/html/draft-shen-sm3-hash-01
+ *
+ * Copyright (C) 2017 ARM Limited or its affiliates.
+ * Written by Gilad Ben-Yossef <gilad@benyossef.com>
+ * Copyright (C) 2021 Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
+ * Copyright 2026 Google LLC
+ */
+
+#include <crypto/internal/hash.h>
+#include <crypto/sm3.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#define SM3_CTX(desc) ((struct sm3_ctx *)shash_desc_ctx(desc))
+
+static int crypto_sm3_init(struct shash_desc *desc)
+{
+	sm3_init(SM3_CTX(desc));
+	return 0;
+}
+
+static int crypto_sm3_update(struct shash_desc *desc,
+			     const u8 *data, unsigned int len)
+{
+	sm3_update(SM3_CTX(desc), data, len);
+	return 0;
+}
+
+static int crypto_sm3_final(struct shash_desc *desc, u8 *out)
+{
+	sm3_final(SM3_CTX(desc), out);
+	return 0;
+}
+
+static int crypto_sm3_digest(struct shash_desc *desc,
+			     const u8 *data, unsigned int len, u8 *out)
+{
+	sm3(data, len, out);
+	return 0;
+}
+
+static int crypto_sm3_export_core(struct shash_desc *desc, void *out)
+{
+	memcpy(out, SM3_CTX(desc), sizeof(struct sm3_ctx));
+	return 0;
+}
+
+static int crypto_sm3_import_core(struct shash_desc *desc, const void *in)
+{
+	memcpy(SM3_CTX(desc), in, sizeof(struct sm3_ctx));
+	return 0;
+}
+
+static struct shash_alg sm3_alg = {
+	.base.cra_name		= "sm3",
+	.base.cra_driver_name	= "sm3-lib",
+	.base.cra_priority	= 300,
+	.base.cra_blocksize	= SM3_BLOCK_SIZE,
+	.base.cra_module	= THIS_MODULE,
+	.digestsize		= SM3_DIGEST_SIZE,
+	.init			= crypto_sm3_init,
+	.update			= crypto_sm3_update,
+	.final			= crypto_sm3_final,
+	.digest			= crypto_sm3_digest,
+	.export_core		= crypto_sm3_export_core,
+	.import_core		= crypto_sm3_import_core,
+	.descsize		= sizeof(struct sm3_ctx),
+};
+
+static int __init crypto_sm3_mod_init(void)
+{
+	return crypto_register_shash(&sm3_alg);
+}
+module_init(crypto_sm3_mod_init);
+
+static void __exit crypto_sm3_mod_exit(void)
+{
+	crypto_unregister_shash(&sm3_alg);
+}
+module_exit(crypto_sm3_mod_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Crypto API support for SM3");
+
+MODULE_ALIAS_CRYPTO("sm3");
+MODULE_ALIAS_CRYPTO("sm3-lib");