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, 79 insertions, 0 deletions

diff --git a/sound/soc/sof/sof-client.h b/sound/soc/sof/sof-client.h
new file mode 100644
index 000000000..3b02506c0
--- /dev/null
+++ b/sound/soc/sof/sof-client.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __SOC_SOF_CLIENT_H
+#define __SOC_SOF_CLIENT_H
+
+#include <linux/auxiliary_bus.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <sound/sof.h>
+
+struct sof_ipc_fw_version;
+struct sof_ipc_cmd_hdr;
+struct snd_sof_dev;
+struct dentry;
+
+struct sof_ipc4_fw_module;
+
+/**
+ * struct sof_client_dev - SOF client device
+ * @auxdev:	auxiliary device
+ * @data:	device specific data
+ */
+struct sof_client_dev {
+	struct auxiliary_device auxdev;
+	void *data;
+};
+
+#define auxiliary_dev_to_sof_client_dev(auxiliary_dev) \
+	container_of(auxiliary_dev, struct sof_client_dev, auxdev)
+
+#define dev_to_sof_client_dev(dev) \
+	container_of(to_auxiliary_dev(dev), struct sof_client_dev, auxdev)
+
+int sof_client_ipc_tx_message(struct sof_client_dev *cdev, void *ipc_msg,
+			      void *reply_data, size_t reply_bytes);
+static inline int sof_client_ipc_tx_message_no_reply(struct sof_client_dev *cdev, void *ipc_msg)
+{
+	return sof_client_ipc_tx_message(cdev, ipc_msg, NULL, 0);
+}
+int sof_client_ipc_set_get_data(struct sof_client_dev *cdev, void *ipc_msg,
+				bool set);
+
+struct sof_ipc4_fw_module *sof_client_ipc4_find_module(struct sof_client_dev *c, const guid_t *u);
+struct snd_sof_widget *sof_client_ipc4_find_swidget_by_id(struct sof_client_dev *cdev,
+							  u32 module_id, int instance_id);
+
+struct dentry *sof_client_get_debugfs_root(struct sof_client_dev *cdev);
+struct device *sof_client_get_dma_dev(struct sof_client_dev *cdev);
+const struct sof_ipc_fw_version *sof_client_get_fw_version(struct sof_client_dev *cdev);
+size_t sof_client_get_ipc_max_payload_size(struct sof_client_dev *cdev);
+enum sof_ipc_type sof_client_get_ipc_type(struct sof_client_dev *cdev);
+
+/* DSP/firmware boot request */
+int sof_client_boot_dsp(struct sof_client_dev *cdev);
+
+/* module refcount management of SOF core */
+int sof_client_core_module_get(struct sof_client_dev *cdev);
+void sof_client_core_module_put(struct sof_client_dev *cdev);
+
+/* IPC notification */
+typedef void (*sof_client_event_callback)(struct sof_client_dev *cdev, void *msg_buf);
+
+int sof_client_register_ipc_rx_handler(struct sof_client_dev *cdev,
+				       u32 ipc_msg_type,
+				       sof_client_event_callback callback);
+void sof_client_unregister_ipc_rx_handler(struct sof_client_dev *cdev,
+					  u32 ipc_msg_type);
+
+/* DSP state notification and query */
+typedef void (*sof_client_fw_state_callback)(struct sof_client_dev *cdev,
+					     enum sof_fw_state state);
+
+int sof_client_register_fw_state_handler(struct sof_client_dev *cdev,
+					 sof_client_fw_state_callback callback);
+void sof_client_unregister_fw_state_handler(struct sof_client_dev *cdev);
+enum sof_fw_state sof_client_get_fw_state(struct sof_client_dev *cdev);
+int sof_client_ipc_rx_message(struct sof_client_dev *cdev, void *ipc_msg, void *msg_buf);
+
+#endif /* __SOC_SOF_CLIENT_H */