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, 88 insertions, 0 deletions

diff --git a/drivers/net/Makefile b/drivers/net/Makefile
new file mode 100644
index 000000000..88e4c485d
--- /dev/null
+++ b/drivers/net/Makefile
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Linux network device drivers.
+#
+
+#
+# Networking Core Drivers
+#
+obj-$(CONFIG_BONDING) += bonding/
+obj-$(CONFIG_IPVLAN) += ipvlan/
+obj-$(CONFIG_IPVTAP) += ipvlan/
+obj-$(CONFIG_DUMMY) += dummy.o
+obj-$(CONFIG_WIREGUARD) += wireguard/
+obj-$(CONFIG_OVPN) += ovpn/
+obj-$(CONFIG_EQUALIZER) += eql.o
+obj-$(CONFIG_IFB) += ifb.o
+obj-$(CONFIG_MACSEC) += macsec.o
+obj-$(CONFIG_AMT) += amt.o
+obj-$(CONFIG_MACVLAN) += macvlan.o
+obj-$(CONFIG_MACVTAP) += macvtap.o
+obj-$(CONFIG_MII) += mii.o
+obj-$(CONFIG_MDIO) += mdio.o
+obj-$(CONFIG_NET) += loopback.o
+obj-$(CONFIG_NETCONSOLE) += netconsole.o
+obj-$(CONFIG_NETKIT) += netkit.o
+obj-y += phy/
+obj-y += pse-pd/
+obj-y += mdio/
+obj-y += pcs/
+obj-$(CONFIG_RIONET) += rionet.o
+obj-$(CONFIG_NET_TEAM) += team/
+obj-$(CONFIG_TUN) += tun.o
+obj-$(CONFIG_TAP) += tap.o
+obj-$(CONFIG_VETH) += veth.o
+obj-$(CONFIG_VIRTIO_NET) += virtio_net.o
+obj-$(CONFIG_VXLAN) += vxlan/
+obj-$(CONFIG_GENEVE) += geneve.o
+obj-$(CONFIG_BAREUDP) += bareudp.o
+obj-$(CONFIG_GTP) += gtp.o
+obj-$(CONFIG_NLMON) += nlmon.o
+obj-$(CONFIG_PFCP) += pfcp.o
+obj-$(CONFIG_NET_VRF) += vrf.o
+obj-$(CONFIG_VSOCKMON) += vsockmon.o
+obj-$(CONFIG_MHI_NET) += mhi_net.o
+
+#
+# Networking Drivers
+#
+obj-$(CONFIG_ARCNET) += arcnet/
+obj-$(CONFIG_CAN) += can/
+ifdef CONFIG_NET_DSA
+obj-y += dsa/
+endif
+obj-$(CONFIG_ETHERNET) += ethernet/
+obj-$(CONFIG_FDDI) += fddi/
+obj-$(CONFIG_QCOM_IPA) += ipa/
+obj-$(CONFIG_PLIP) += plip/
+obj-$(CONFIG_PPP) += ppp/
+obj-$(CONFIG_PPP_ASYNC) += ppp/
+obj-$(CONFIG_PPP_BSDCOMP) += ppp/
+obj-$(CONFIG_PPP_DEFLATE) += ppp/
+obj-$(CONFIG_PPP_MPPE) += ppp/
+obj-$(CONFIG_PPP_SYNC_TTY) += ppp/
+obj-$(CONFIG_PPPOE) += ppp/
+obj-$(CONFIG_PPPOL2TP) += ppp/
+obj-$(CONFIG_PPTP) += ppp/
+obj-$(CONFIG_SLIP) += slip/
+obj-$(CONFIG_SLHC) += slip/
+obj-$(CONFIG_SUNGEM_PHY) += sungem_phy.o
+obj-$(CONFIG_WAN) += wan/
+obj-$(CONFIG_WLAN) += wireless/
+obj-$(CONFIG_IEEE802154) += ieee802154/
+obj-$(CONFIG_WWAN) += wwan/
+obj-$(CONFIG_MCTP) += mctp/
+
+obj-$(CONFIG_VMXNET3) += vmxnet3/
+obj-$(CONFIG_XEN_NETDEV_FRONTEND) += xen-netfront.o
+obj-$(CONFIG_XEN_NETDEV_BACKEND) += xen-netback/
+
+obj-$(CONFIG_USB_NET_DRIVERS) += usb/
+
+obj-$(CONFIG_HYPERV_NET) += hyperv/
+obj-$(CONFIG_NTB_NETDEV) += ntb_netdev.o
+
+obj-$(CONFIG_FUJITSU_ES) += fjes/
+obj-$(CONFIG_USB4_NET) += thunderbolt/
+obj-$(CONFIG_NETDEVSIM) += netdevsim/
+obj-$(CONFIG_NET_FAILOVER) += net_failover.o