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>

2 files changed, 116 insertions, 0 deletions

diff --git a/include/media/davinci/vpfe_types.h b/include/media/davinci/vpfe_types.h
new file mode 100644
index 000000000..e65c9a48d
--- /dev/null
+++ b/include/media/davinci/vpfe_types.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2008-2009 Texas Instruments Inc
+ */
+#ifndef _VPFE_TYPES_H
+#define _VPFE_TYPES_H
+
+#ifdef __KERNEL__
+
+enum vpfe_pin_pol {
+	VPFE_PINPOL_POSITIVE,
+	VPFE_PINPOL_NEGATIVE
+};
+
+enum vpfe_hw_if_type {
+	/* BT656 - 8 bit */
+	VPFE_BT656,
+	/* BT1120 - 16 bit */
+	VPFE_BT1120,
+	/* Raw Bayer */
+	VPFE_RAW_BAYER,
+	/* YCbCr - 8 bit with external sync */
+	VPFE_YCBCR_SYNC_8,
+	/* YCbCr - 16 bit with external sync */
+	VPFE_YCBCR_SYNC_16,
+	/* BT656 - 10 bit */
+	VPFE_BT656_10BIT
+};
+
+/* interface description */
+struct vpfe_hw_if_param {
+	enum vpfe_hw_if_type if_type;
+	enum vpfe_pin_pol hdpol;
+	enum vpfe_pin_pol vdpol;
+};
+
+#endif
+#endif
diff --git a/include/media/davinci/vpif_types.h b/include/media/davinci/vpif_types.h
new file mode 100644
index 000000000..6cce1f09c
--- /dev/null
+++ b/include/media/davinci/vpif_types.h
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2011 Texas Instruments Inc
+ */
+#ifndef _VPIF_TYPES_H
+#define _VPIF_TYPES_H
+
+#include <linux/i2c.h>
+
+#define VPIF_CAPTURE_MAX_CHANNELS	2
+#define VPIF_DISPLAY_MAX_CHANNELS	2
+
+enum vpif_if_type {
+	VPIF_IF_BT656,
+	VPIF_IF_BT1120,
+	VPIF_IF_RAW_BAYER
+};
+
+struct vpif_interface {
+	enum vpif_if_type if_type;
+	unsigned hd_pol:1;
+	unsigned vd_pol:1;
+	unsigned fid_pol:1;
+};
+
+struct vpif_subdev_info {
+	const char *name;
+	struct i2c_board_info board_info;
+};
+
+struct vpif_output {
+	struct v4l2_output output;
+	const char *subdev_name;
+	u32 input_route;
+	u32 output_route;
+};
+
+struct vpif_display_chan_config {
+	const struct vpif_output *outputs;
+	int output_count;
+	bool clip_en;
+};
+
+struct vpif_display_config {
+	int (*set_clock)(int, int);
+	struct vpif_subdev_info *subdevinfo;
+	int subdev_count;
+	int i2c_adapter_id;
+	struct vpif_display_chan_config chan_config[VPIF_DISPLAY_MAX_CHANNELS];
+	const char *card_name;
+};
+
+struct vpif_input {
+	struct v4l2_input input;
+	char *subdev_name;
+	u32 input_route;
+	u32 output_route;
+};
+
+struct vpif_capture_chan_config {
+	struct vpif_interface vpif_if;
+	struct vpif_input *inputs;
+	int input_count;
+};
+
+struct vpif_capture_config {
+	int (*setup_input_channel_mode)(int);
+	int (*setup_input_path)(int, const char *);
+	struct vpif_capture_chan_config chan_config[VPIF_CAPTURE_MAX_CHANNELS];
+	struct vpif_subdev_info *subdev_info;
+	int subdev_count;
+	int i2c_adapter_id;
+	const char *card_name;
+
+	struct v4l2_async_connection *asd[VPIF_CAPTURE_MAX_CHANNELS];
+	int asd_sizes[VPIF_CAPTURE_MAX_CHANNELS];
+};
+#endif /* _VPIF_TYPES_H */