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, 18 insertions, 0 deletions

diff --git a/lib/crypto/tests/Makefile b/lib/crypto/tests/Makefile
new file mode 100644
index 000000000..a73941350
--- /dev/null
+++ b/lib/crypto/tests/Makefile
@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+obj-$(CONFIG_CRYPTO_LIB_AES_CBC_MACS_KUNIT_TEST) += aes_cbc_macs_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_BLAKE2B_KUNIT_TEST) += blake2b_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_BLAKE2S_KUNIT_TEST) += blake2s_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_CHACHA20POLY1305_KUNIT_TEST) += chacha20poly1305_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_CURVE25519_KUNIT_TEST) += curve25519_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_GHASH_KUNIT_TEST) += ghash_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_MD5_KUNIT_TEST) += md5_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_MLDSA_KUNIT_TEST) += mldsa_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_NH_KUNIT_TEST) += nh_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_POLY1305_KUNIT_TEST) += poly1305_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_POLYVAL_KUNIT_TEST) += polyval_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_SHA1_KUNIT_TEST) += sha1_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_SHA256_KUNIT_TEST) += sha224_kunit.o sha256_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_SHA512_KUNIT_TEST) += sha384_kunit.o sha512_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_SHA3_KUNIT_TEST) += sha3_kunit.o
+obj-$(CONFIG_CRYPTO_LIB_SM3_KUNIT_TEST) += sm3_kunit.o