From 1039bffd6ae9c75b42b7d148d6c1106134107b66 Mon Sep 17 00:00:00 2001 From: Xie Yuanbin Date: Tue, 28 Jul 2026 03:16:42 +0100 Subject: ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faults 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 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) Reviewed-by: Linus Walleij Signed-off-by: Qi Xi Signed-off-by: Xie Yuanbin Signed-off-by: Russell King --- include/drm/intel/step.h | 62 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) create mode 100644 include/drm/intel/step.h (limited to 'include/drm/intel/step.h') diff --git a/include/drm/intel/step.h b/include/drm/intel/step.h new file mode 100644 index 000000000..4de752010 --- /dev/null +++ b/include/drm/intel/step.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: MIT */ +/* Copyright © 2026 Intel Corporation */ + +#ifndef __STEP_H__ +#define __STEP_H__ + +#define STEP_ENUM_VAL(name) STEP_##name, + +#define STEP_NAME_LIST(func) \ + func(A0) \ + func(A1) \ + func(A2) \ + func(A3) \ + func(B0) \ + func(B1) \ + func(B2) \ + func(B3) \ + func(C0) \ + func(C1) \ + func(C2) \ + func(C3) \ + func(D0) \ + func(D1) \ + func(D2) \ + func(D3) \ + func(E0) \ + func(E1) \ + func(E2) \ + func(E3) \ + func(F0) \ + func(F1) \ + func(F2) \ + func(F3) \ + func(G0) \ + func(G1) \ + func(G2) \ + func(G3) \ + func(H0) \ + func(H1) \ + func(H2) \ + func(H3) \ + func(I0) \ + func(I1) \ + func(I2) \ + func(I3) \ + func(J0) \ + func(J1) \ + func(J2) \ + func(J3) + +/* + * Symbolic steppings that do not match the hardware. These are valid both as gt + * and display steppings as symbolic names. + */ +enum intel_step { + STEP_NONE = 0, + STEP_NAME_LIST(STEP_ENUM_VAL) + STEP_FUTURE, + STEP_FOREVER, +}; + +#endif /* __STEP_H__ */ -- cgit v1.3.1