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, 127 insertions, 0 deletions

diff --git a/include/soc/tegra/fuse.h b/include/soc/tegra/fuse.h
new file mode 100644
index 000000000..8f421b9f7
--- /dev/null
+++ b/include/soc/tegra/fuse.h
@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2012-2023, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#ifndef __SOC_TEGRA_FUSE_H__
+#define __SOC_TEGRA_FUSE_H__
+
+#include <linux/types.h>
+
+#define TEGRA20		0x20
+#define TEGRA30		0x30
+#define TEGRA114	0x35
+#define TEGRA124	0x40
+#define TEGRA132	0x13
+#define TEGRA210	0x21
+#define TEGRA186	0x18
+#define TEGRA194	0x19
+#define TEGRA234	0x23
+#define TEGRA241	0x24
+#define TEGRA264	0x26
+
+#define TEGRA_FUSE_SKU_CALIB_0	0xf0
+#define TEGRA30_FUSE_SATA_CALIB	0x124
+#define TEGRA_FUSE_USB_CALIB_EXT_0 0x250
+
+#ifndef __ASSEMBLY__
+
+enum tegra_revision {
+	TEGRA_REVISION_UNKNOWN = 0,
+	TEGRA_REVISION_A01,
+	TEGRA_REVISION_A02,
+	TEGRA_REVISION_A03,
+	TEGRA_REVISION_A03p,
+	TEGRA_REVISION_A04,
+	TEGRA_REVISION_MAX,
+};
+
+enum tegra_platform {
+	TEGRA_PLATFORM_SILICON = 0,
+	TEGRA_PLATFORM_QT,
+	TEGRA_PLATFORM_SYSTEM_FPGA,
+	TEGRA_PLATFORM_UNIT_FPGA,
+	TEGRA_PLATFORM_ASIM_QT,
+	TEGRA_PLATFORM_ASIM_LINSIM,
+	TEGRA_PLATFORM_DSIM_ASIM_LINSIM,
+	TEGRA_PLATFORM_VERIFICATION_SIMULATION,
+	TEGRA_PLATFORM_VDK,
+	TEGRA_PLATFORM_VSP,
+	TEGRA_PLATFORM_MAX,
+};
+
+struct tegra_sku_info {
+	int sku_id;
+	int cpu_process_id;
+	int cpu_speedo_id;
+	int cpu_speedo_value;
+	int cpu_iddq_value;
+	int soc_process_id;
+	int soc_speedo_id;
+	int soc_speedo_value;
+	int gpu_process_id;
+	int gpu_speedo_id;
+	int gpu_speedo_value;
+	enum tegra_revision revision;
+	enum tegra_platform platform;
+};
+
+#ifdef CONFIG_ARCH_TEGRA
+extern struct tegra_sku_info tegra_sku_info;
+u32 tegra_read_straps(void);
+u32 tegra_read_ram_code(void);
+int tegra_fuse_readl(unsigned long offset, u32 *value);
+u32 tegra_read_chipid(void);
+u8 tegra_get_chip_id(void);
+u8 tegra_get_platform(void);
+bool tegra_is_silicon(void);
+int tegra194_miscreg_mask_serror(void);
+#else
+static struct tegra_sku_info tegra_sku_info __maybe_unused;
+
+static inline u32 tegra_read_straps(void)
+{
+	return 0;
+}
+
+static inline u32 tegra_read_ram_code(void)
+{
+	return 0;
+}
+
+static inline int tegra_fuse_readl(unsigned long offset, u32 *value)
+{
+	return -ENODEV;
+}
+
+static inline u32 tegra_read_chipid(void)
+{
+	return 0;
+}
+
+static inline u8 tegra_get_chip_id(void)
+{
+	return 0;
+}
+
+static inline u8 tegra_get_platform(void)
+{
+	return 0;
+}
+
+static inline bool tegra_is_silicon(void)
+{
+	return false;
+}
+
+static inline int tegra194_miscreg_mask_serror(void)
+{
+	return false;
+}
+#endif
+
+struct device *tegra_soc_device_register(void);
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __SOC_TEGRA_FUSE_H__ */