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, 75 insertions, 0 deletions

diff --git a/net/ethtool/module_fw.h b/net/ethtool/module_fw.h
new file mode 100644
index 000000000..634543a12
--- /dev/null
+++ b/net/ethtool/module_fw.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <uapi/linux/ethtool.h>
+#include "netlink.h"
+
+/**
+ * struct ethnl_module_fw_flash_ntf_params - module firmware flashing
+ *						notifications parameters
+ * @portid: Netlink portid of sender.
+ * @seq: Sequence number of sender.
+ * @closed_sock: Indicates whether the socket was closed from user space.
+ */
+struct ethnl_module_fw_flash_ntf_params {
+	u32 portid;
+	u32 seq;
+	bool closed_sock;
+};
+
+/**
+ * struct ethtool_module_fw_flash_params - module firmware flashing parameters
+ * @password: Module password. Only valid when @pass_valid is set.
+ * @password_valid: Whether the module password is valid or not.
+ */
+struct ethtool_module_fw_flash_params {
+	__be32 password;
+	u8 password_valid:1;
+};
+
+/**
+ * struct ethtool_cmis_fw_update_params - CMIS firmware update specific
+ *						parameters
+ * @dev: Pointer to the net_device to be flashed.
+ * @params: Module firmware flashing parameters.
+ * @ntf_params: Module firmware flashing notification parameters.
+ * @fw: Firmware to flash.
+ */
+struct ethtool_cmis_fw_update_params {
+	struct net_device *dev;
+	struct ethtool_module_fw_flash_params params;
+	struct ethnl_module_fw_flash_ntf_params ntf_params;
+	const struct firmware *fw;
+};
+
+/**
+ * struct ethtool_module_fw_flash - module firmware flashing
+ * @list: List node for &module_fw_flash_work_list.
+ * @dev_tracker: Refcount tracker for @dev.
+ * @work: The flashing firmware work.
+ * @fw_update: CMIS firmware update specific parameters.
+ */
+struct ethtool_module_fw_flash {
+	struct list_head list;
+	netdevice_tracker dev_tracker;
+	struct work_struct work;
+	struct ethtool_cmis_fw_update_params fw_update;
+};
+
+void ethnl_module_fw_flash_sock_destroy(struct ethnl_sock_priv *sk_priv);
+
+void
+ethnl_module_fw_flash_ntf_err(struct net_device *dev,
+			      struct ethnl_module_fw_flash_ntf_params *params,
+			      char *err_msg, char *sub_err_msg);
+void
+ethnl_module_fw_flash_ntf_start(struct net_device *dev,
+				struct ethnl_module_fw_flash_ntf_params *params);
+void
+ethnl_module_fw_flash_ntf_complete(struct net_device *dev,
+				   struct ethnl_module_fw_flash_ntf_params *params);
+void
+ethnl_module_fw_flash_ntf_in_progress(struct net_device *dev,
+				      struct ethnl_module_fw_flash_ntf_params *params,
+				      u64 done, u64 total);
+
+void ethtool_cmis_fw_update(struct ethtool_cmis_fw_update_params *params);