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, 53 insertions, 0 deletions

diff --git a/sound/soc/sof/trace.c b/sound/soc/sof/trace.c
new file mode 100644
index 000000000..fe6c67c01
--- /dev/null
+++ b/sound/soc/sof/trace.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright(c) 2022 Intel Corporation
+
+#include "sof-priv.h"
+
+int sof_fw_trace_init(struct snd_sof_dev *sdev)
+{
+	const struct sof_ipc_fw_tracing_ops *fw_tracing = sof_ipc_get_ops(sdev, fw_tracing);
+
+	if (!fw_tracing) {
+		dev_info(sdev->dev, "Firmware tracing is not available\n");
+		sdev->fw_trace_is_supported = false;
+
+		return 0;
+	}
+
+	return fw_tracing->init(sdev);
+}
+
+void sof_fw_trace_free(struct snd_sof_dev *sdev)
+{
+	if (!sdev->fw_trace_is_supported)
+		return;
+
+	if (sdev->ipc->ops->fw_tracing->free)
+		sdev->ipc->ops->fw_tracing->free(sdev);
+}
+
+void sof_fw_trace_fw_crashed(struct snd_sof_dev *sdev)
+{
+	if (!sdev->fw_trace_is_supported)
+		return;
+
+	if (sdev->ipc->ops->fw_tracing->fw_crashed)
+		sdev->ipc->ops->fw_tracing->fw_crashed(sdev);
+}
+
+void sof_fw_trace_suspend(struct snd_sof_dev *sdev, pm_message_t pm_state)
+{
+	if (!sdev->fw_trace_is_supported)
+		return;
+
+	sdev->ipc->ops->fw_tracing->suspend(sdev, pm_state);
+}
+
+int sof_fw_trace_resume(struct snd_sof_dev *sdev)
+{
+	if (!sdev->fw_trace_is_supported)
+		return 0;
+
+	return sdev->ipc->ops->fw_tracing->resume(sdev);
+}