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, 84 insertions, 0 deletions

diff --git a/include/dt-bindings/display/sdtv-standards.h b/include/dt-bindings/display/sdtv-standards.h
new file mode 100644
index 000000000..8249a2b47
--- /dev/null
+++ b/include/dt-bindings/display/sdtv-standards.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR X11 */
+/*
+ * Copyright 2019 Pengutronix, Marco Felsch <kernel@pengutronix.de>
+ */
+
+#ifndef _DT_BINDINGS_DISPLAY_SDTV_STDS_H
+#define _DT_BINDINGS_DISPLAY_SDTV_STDS_H
+
+/*
+ * Attention: Keep the SDTV_STD_* bit definitions in sync with
+ * include/uapi/linux/videodev2.h V4L2_STD_* bit definitions.
+ */
+/* One bit for each standard */
+#define SDTV_STD_PAL_B		0x00000001
+#define SDTV_STD_PAL_B1		0x00000002
+#define SDTV_STD_PAL_G		0x00000004
+#define SDTV_STD_PAL_H		0x00000008
+#define SDTV_STD_PAL_I		0x00000010
+#define SDTV_STD_PAL_D		0x00000020
+#define SDTV_STD_PAL_D1		0x00000040
+#define SDTV_STD_PAL_K		0x00000080
+
+#define SDTV_STD_PAL		(SDTV_STD_PAL_B		| \
+				 SDTV_STD_PAL_B1	| \
+				 SDTV_STD_PAL_G		| \
+				 SDTV_STD_PAL_H		| \
+				 SDTV_STD_PAL_I		| \
+				 SDTV_STD_PAL_D		| \
+				 SDTV_STD_PAL_D1	| \
+				 SDTV_STD_PAL_K)
+
+#define SDTV_STD_PAL_M		0x00000100
+#define SDTV_STD_PAL_N		0x00000200
+#define SDTV_STD_PAL_Nc		0x00000400
+#define SDTV_STD_PAL_60		0x00000800
+
+#define SDTV_STD_NTSC_M		0x00001000	/* BTSC */
+#define SDTV_STD_NTSC_M_JP	0x00002000	/* EIA-J */
+#define SDTV_STD_NTSC_443	0x00004000
+#define SDTV_STD_NTSC_M_KR	0x00008000	/* FM A2 */
+
+#define SDTV_STD_NTSC		(SDTV_STD_NTSC_M	| \
+				 SDTV_STD_NTSC_M_JP	| \
+				 SDTV_STD_NTSC_M_KR)
+
+#define SDTV_STD_SECAM_B	0x00010000
+#define SDTV_STD_SECAM_D	0x00020000
+#define SDTV_STD_SECAM_G	0x00040000
+#define SDTV_STD_SECAM_H	0x00080000
+#define SDTV_STD_SECAM_K	0x00100000
+#define SDTV_STD_SECAM_K1	0x00200000
+#define SDTV_STD_SECAM_L	0x00400000
+#define SDTV_STD_SECAM_LC	0x00800000
+
+#define SDTV_STD_SECAM		(SDTV_STD_SECAM_B	| \
+				 SDTV_STD_SECAM_D	| \
+				 SDTV_STD_SECAM_G	| \
+				 SDTV_STD_SECAM_H	| \
+				 SDTV_STD_SECAM_K	| \
+				 SDTV_STD_SECAM_K1	| \
+				 SDTV_STD_SECAM_L	| \
+				 SDTV_STD_SECAM_LC)
+
+/* Standards for Countries with 60Hz Line frequency */
+#define SDTV_STD_525_60		(SDTV_STD_PAL_M		| \
+				 SDTV_STD_PAL_60	| \
+				 SDTV_STD_NTSC		| \
+				 SDTV_STD_NTSC_443)
+
+/* Standards for Countries with 50Hz Line frequency */
+#define SDTV_STD_625_50		(SDTV_STD_PAL		| \
+				 SDTV_STD_PAL_N		| \
+				 SDTV_STD_PAL_Nc	| \
+				 SDTV_STD_SECAM)
+
+#endif /* _DT_BINDINGS_DISPLAY_SDTV_STDS_H */
diff --git a/include/dt-bindings/display/tda998x.h b/include/dt-bindings/display/tda998x.h
new file mode 100644
index 000000000..746831ff3
--- /dev/null
+++ b/include/dt-bindings/display/tda998x.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _DT_BINDINGS_TDA998X_H
+#define _DT_BINDINGS_TDA998X_H
+
+#define TDA998x_SPDIF	1
+#define TDA998x_I2S	2
+
+#endif /*_DT_BINDINGS_TDA998X_H */