ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faultsgrafted

When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
a user fault may trigger show_pte() without any lock.
If another thread in the same process concurrently calls munmap(),
the page table pages may be freed while show_pte() is still traversing
them, causing a use-after-free in show_pte().

If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table
of PMD are freed when show_pte() is running.

Acquire mmap_write_lock() around show_pte() for user faults to fix the
contention.

For user faults, additionally restrict that show_pte() is called only
when the addr is a user-space address (addr < TASK_SIZE). This is because
the lock of tsk->mm only protects the virtual memory of user address space,
furthermore, dumping the page tables of a kernel-space address for user
faults is unnecessary and may have security implications.

Keep everything unchanged for kernel faults, because the kernel is
already in the "oops" state, acquiring a lock may risk a deadlock.

Co-developed-by: Qi Xi <xiqi2@huawei.com>

Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults")
Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

1 files changed, 166 insertions, 0 deletions

diff --git a/crypto/sha3.c b/crypto/sha3.c
new file mode 100644
index 000000000..8f364979e
--- /dev/null
+++ b/crypto/sha3.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Crypto API support for SHA-3
+ * (https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf)
+ */
+#include <crypto/internal/hash.h>
+#include <crypto/sha3.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#define SHA3_CTX(desc) ((struct sha3_ctx *)shash_desc_ctx(desc))
+
+static int crypto_sha3_224_init(struct shash_desc *desc)
+{
+	sha3_224_init(SHA3_CTX(desc));
+	return 0;
+}
+
+static int crypto_sha3_256_init(struct shash_desc *desc)
+{
+	sha3_256_init(SHA3_CTX(desc));
+	return 0;
+}
+
+static int crypto_sha3_384_init(struct shash_desc *desc)
+{
+	sha3_384_init(SHA3_CTX(desc));
+	return 0;
+}
+
+static int crypto_sha3_512_init(struct shash_desc *desc)
+{
+	sha3_512_init(SHA3_CTX(desc));
+	return 0;
+}
+
+static int crypto_sha3_update(struct shash_desc *desc, const u8 *data,
+			      unsigned int len)
+{
+	sha3_update(SHA3_CTX(desc), data, len);
+	return 0;
+}
+
+static int crypto_sha3_final(struct shash_desc *desc, u8 *out)
+{
+	sha3_final(SHA3_CTX(desc), out);
+	return 0;
+}
+
+static int crypto_sha3_224_digest(struct shash_desc *desc,
+				  const u8 *data, unsigned int len, u8 *out)
+{
+	sha3_224(data, len, out);
+	return 0;
+}
+
+static int crypto_sha3_256_digest(struct shash_desc *desc,
+				  const u8 *data, unsigned int len, u8 *out)
+{
+	sha3_256(data, len, out);
+	return 0;
+}
+
+static int crypto_sha3_384_digest(struct shash_desc *desc,
+				  const u8 *data, unsigned int len, u8 *out)
+{
+	sha3_384(data, len, out);
+	return 0;
+}
+
+static int crypto_sha3_512_digest(struct shash_desc *desc,
+				  const u8 *data, unsigned int len, u8 *out)
+{
+	sha3_512(data, len, out);
+	return 0;
+}
+
+static int crypto_sha3_export_core(struct shash_desc *desc, void *out)
+{
+	memcpy(out, SHA3_CTX(desc), sizeof(struct sha3_ctx));
+	return 0;
+}
+
+static int crypto_sha3_import_core(struct shash_desc *desc, const void *in)
+{
+	memcpy(SHA3_CTX(desc), in, sizeof(struct sha3_ctx));
+	return 0;
+}
+
+static struct shash_alg algs[] = { {
+	.digestsize		= SHA3_224_DIGEST_SIZE,
+	.init			= crypto_sha3_224_init,
+	.update			= crypto_sha3_update,
+	.final			= crypto_sha3_final,
+	.digest			= crypto_sha3_224_digest,
+	.export_core		= crypto_sha3_export_core,
+	.import_core		= crypto_sha3_import_core,
+	.descsize		= sizeof(struct sha3_ctx),
+	.base.cra_name		= "sha3-224",
+	.base.cra_driver_name	= "sha3-224-lib",
+	.base.cra_blocksize	= SHA3_224_BLOCK_SIZE,
+	.base.cra_module	= THIS_MODULE,
+}, {
+	.digestsize		= SHA3_256_DIGEST_SIZE,
+	.init			= crypto_sha3_256_init,
+	.update			= crypto_sha3_update,
+	.final			= crypto_sha3_final,
+	.digest			= crypto_sha3_256_digest,
+	.export_core		= crypto_sha3_export_core,
+	.import_core		= crypto_sha3_import_core,
+	.descsize		= sizeof(struct sha3_ctx),
+	.base.cra_name		= "sha3-256",
+	.base.cra_driver_name	= "sha3-256-lib",
+	.base.cra_blocksize	= SHA3_256_BLOCK_SIZE,
+	.base.cra_module	= THIS_MODULE,
+}, {
+	.digestsize		= SHA3_384_DIGEST_SIZE,
+	.init			= crypto_sha3_384_init,
+	.update			= crypto_sha3_update,
+	.final			= crypto_sha3_final,
+	.digest			= crypto_sha3_384_digest,
+	.export_core		= crypto_sha3_export_core,
+	.import_core		= crypto_sha3_import_core,
+	.descsize		= sizeof(struct sha3_ctx),
+	.base.cra_name		= "sha3-384",
+	.base.cra_driver_name	= "sha3-384-lib",
+	.base.cra_blocksize	= SHA3_384_BLOCK_SIZE,
+	.base.cra_module	= THIS_MODULE,
+}, {
+	.digestsize		= SHA3_512_DIGEST_SIZE,
+	.init			= crypto_sha3_512_init,
+	.update			= crypto_sha3_update,
+	.final			= crypto_sha3_final,
+	.digest			= crypto_sha3_512_digest,
+	.export_core		= crypto_sha3_export_core,
+	.import_core		= crypto_sha3_import_core,
+	.descsize		= sizeof(struct sha3_ctx),
+	.base.cra_name		= "sha3-512",
+	.base.cra_driver_name	= "sha3-512-lib",
+	.base.cra_blocksize	= SHA3_512_BLOCK_SIZE,
+	.base.cra_module	= THIS_MODULE,
+} };
+
+static int __init crypto_sha3_mod_init(void)
+{
+	return crypto_register_shashes(algs, ARRAY_SIZE(algs));
+}
+module_init(crypto_sha3_mod_init);
+
+static void __exit crypto_sha3_mod_exit(void)
+{
+	crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
+}
+module_exit(crypto_sha3_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Crypto API support for SHA-3");
+
+MODULE_ALIAS_CRYPTO("sha3-224");
+MODULE_ALIAS_CRYPTO("sha3-224-lib");
+MODULE_ALIAS_CRYPTO("sha3-256");
+MODULE_ALIAS_CRYPTO("sha3-256-lib");
+MODULE_ALIAS_CRYPTO("sha3-384");
+MODULE_ALIAS_CRYPTO("sha3-384-lib");
+MODULE_ALIAS_CRYPTO("sha3-512");
+MODULE_ALIAS_CRYPTO("sha3-512-lib");