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, 22 insertions, 0 deletions

diff --git a/drivers/firewire/Makefile b/drivers/firewire/Makefile
new file mode 100644
index 000000000..1ff550e93
--- /dev/null
+++ b/drivers/firewire/Makefile
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Linux IEEE 1394 implementation
+#
+
+firewire-core-y += core-trace.o core-card.o core-cdev.o core-device.o \
+                   core-iso.o core-topology.o core-transaction.o
+firewire-ohci-y += ohci.o
+firewire-sbp2-y += sbp2.o
+firewire-net-y  += net.o
+
+obj-$(CONFIG_FIREWIRE)      += firewire-core.o
+obj-$(CONFIG_FIREWIRE_OHCI) += firewire-ohci.o
+obj-$(CONFIG_FIREWIRE_SBP2) += firewire-sbp2.o
+obj-$(CONFIG_FIREWIRE_NET)  += firewire-net.o
+obj-$(CONFIG_FIREWIRE_NOSY) += nosy.o
+obj-$(CONFIG_PROVIDE_OHCI1394_DMA_INIT) += init_ohci1394_dma.o
+
+obj-$(CONFIG_FIREWIRE_KUNIT_UAPI_TEST) += uapi-test.o
+obj-$(CONFIG_FIREWIRE_KUNIT_PACKET_SERDES_TEST) += packet-serdes-test.o
+obj-$(CONFIG_FIREWIRE_KUNIT_SELF_ID_SEQUENCE_HELPER_TEST) += self-id-sequence-helper-test.o
+obj-$(CONFIG_FIREWIRE_KUNIT_OHCI_SERDES_TEST) += ohci-serdes-test.o