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/net/firewire.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) create mode 100644 include/net/firewire.h (limited to 'include/net/firewire.h') diff --git a/include/net/firewire.h b/include/net/firewire.h new file mode 100644 index 000000000..8fbff8d77 --- /dev/null +++ b/include/net/firewire.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _NET_FIREWIRE_H +#define _NET_FIREWIRE_H + +#include + +/* Pseudo L2 address */ +#define FWNET_ALEN 16 +union fwnet_hwaddr { + u8 u[FWNET_ALEN]; + /* "Hardware address" defined in RFC2734/RF3146 */ + struct { + __be64 uniq_id; /* EUI-64 */ + u8 max_rec; /* max packet size */ + u8 sspd; /* max speed */ + u8 fifo[6]; /* FIFO addr */ + } __packed uc; +}; + +/* Pseudo L2 Header */ +#define FWNET_HLEN 18 +struct fwnet_header { + u8 h_dest[FWNET_ALEN]; /* destination address */ + __be16 h_proto; /* packet type ID field */ +} __packed; + +#endif -- cgit v1.3.1