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, 107 insertions, 0 deletions

diff --git a/include/sound/sof/trace.h b/include/sound/sof/trace.h
new file mode 100644
index 000000000..ac2ebb6fb
--- /dev/null
+++ b/include/sound/sof/trace.h
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * Copyright(c) 2018 Intel Corporation
+ */
+
+#ifndef __INCLUDE_SOUND_SOF_TRACE_H__
+#define __INCLUDE_SOUND_SOF_TRACE_H__
+
+#include <sound/sof/header.h>
+#include <sound/sof/stream.h>
+
+/*
+ * DMA for Trace
+ */
+
+#define SOF_TRACE_FILENAME_SIZE		32
+
+/* DMA for Trace params info - SOF_IPC_DEBUG_DMA_PARAMS */
+/* Deprecated - use sof_ipc_dma_trace_params_ext */
+struct sof_ipc_dma_trace_params {
+	struct sof_ipc_cmd_hdr hdr;
+	struct sof_ipc_host_buffer buffer;
+	uint32_t stream_tag;
+}  __packed;
+
+/* DMA for Trace params info - SOF_IPC_DEBUG_DMA_PARAMS_EXT */
+struct sof_ipc_dma_trace_params_ext {
+	struct sof_ipc_cmd_hdr hdr;
+	struct sof_ipc_host_buffer buffer;
+	uint32_t stream_tag;
+	uint64_t timestamp_ns; /* in nanosecond */
+	uint32_t reserved[8];
+}  __packed;
+
+/* DMA for Trace params info - SOF_IPC_DEBUG_DMA_PARAMS */
+struct sof_ipc_dma_trace_posn {
+	struct sof_ipc_reply rhdr;
+	uint32_t host_offset;	/* Offset of DMA host buffer */
+	uint32_t overflow;	/* overflow bytes if any */
+	uint32_t messages;	/* total trace messages */
+}  __packed;
+
+/* Values used in sof_ipc_trace_filter_elem: */
+
+/* bits 6..0 */
+#define SOF_IPC_TRACE_FILTER_ELEM_SET_LEVEL	0x01	/**< trace level for selected components */
+#define SOF_IPC_TRACE_FILTER_ELEM_BY_UUID	0x02	/**< filter by uuid key */
+#define SOF_IPC_TRACE_FILTER_ELEM_BY_PIPE	0x03	/**< filter by pipeline */
+#define SOF_IPC_TRACE_FILTER_ELEM_BY_COMP	0x04	/**< filter by component id */
+
+/* bit 7 */
+#define SOF_IPC_TRACE_FILTER_ELEM_FIN		0x80	/**< mark last filter in set */
+
+/* bits 31..8: Unused */
+
+/** part of sof_ipc_trace_filter, ABI3.17 */
+struct sof_ipc_trace_filter_elem {
+	uint32_t key;		/**< SOF_IPC_TRACE_FILTER_ELEM_ {LEVEL, UUID, COMP, PIPE} */
+	uint32_t value;		/**< element value */
+} __packed;
+
+/** Runtime tracing filtration data - SOF_IPC_TRACE_FILTER_UPDATE, ABI3.17 */
+struct sof_ipc_trace_filter {
+	struct sof_ipc_cmd_hdr hdr;	/**< IPC command header */
+	uint32_t elem_cnt;		/**< number of entries in elems[] array */
+	uint32_t reserved[8];		/**< reserved for future usage */
+	/** variable size array with new filtering settings */
+	struct sof_ipc_trace_filter_elem elems[];
+} __packed;
+
+/*
+ * Commom debug
+ */
+
+/*
+ * SOF panic codes
+ */
+#define SOF_IPC_PANIC_MAGIC			0x0dead000
+#define SOF_IPC_PANIC_MAGIC_MASK		0x0ffff000
+#define SOF_IPC_PANIC_CODE_MASK			0x00000fff
+#define SOF_IPC_PANIC_MEM			(SOF_IPC_PANIC_MAGIC | 0x0)
+#define SOF_IPC_PANIC_WORK			(SOF_IPC_PANIC_MAGIC | 0x1)
+#define SOF_IPC_PANIC_IPC			(SOF_IPC_PANIC_MAGIC | 0x2)
+#define SOF_IPC_PANIC_ARCH			(SOF_IPC_PANIC_MAGIC | 0x3)
+#define SOF_IPC_PANIC_PLATFORM			(SOF_IPC_PANIC_MAGIC | 0x4)
+#define SOF_IPC_PANIC_TASK			(SOF_IPC_PANIC_MAGIC | 0x5)
+#define SOF_IPC_PANIC_EXCEPTION			(SOF_IPC_PANIC_MAGIC | 0x6)
+#define SOF_IPC_PANIC_DEADLOCK			(SOF_IPC_PANIC_MAGIC | 0x7)
+#define SOF_IPC_PANIC_STACK			(SOF_IPC_PANIC_MAGIC | 0x8)
+#define SOF_IPC_PANIC_IDLE			(SOF_IPC_PANIC_MAGIC | 0x9)
+#define SOF_IPC_PANIC_WFI			(SOF_IPC_PANIC_MAGIC | 0xa)
+#define SOF_IPC_PANIC_ASSERT			(SOF_IPC_PANIC_MAGIC | 0xb)
+
+/* panic info include filename and line number
+ * filename array will not include null terminator if fully filled
+ */
+struct sof_ipc_panic_info {
+	struct sof_ipc_hdr hdr;
+	uint32_t code;			/* SOF_IPC_PANIC_ */
+	uint8_t filename[SOF_TRACE_FILENAME_SIZE];
+	uint32_t linenum;
+}  __packed;
+
+#endif