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/ipconfig.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 include/net/ipconfig.h (limited to 'include/net/ipconfig.h') diff --git a/include/net/ipconfig.h b/include/net/ipconfig.h new file mode 100644 index 000000000..8276897d0 --- /dev/null +++ b/include/net/ipconfig.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 1997 Martin Mares + * + * Automatic IP Layer Configuration + */ + +/* The following are initdata: */ + +#include + +extern int ic_proto_enabled; /* Protocols enabled (see IC_xxx) */ +extern int ic_set_manually; /* IPconfig parameters set manually */ + +extern __be32 ic_myaddr; /* My IP address */ +extern __be32 ic_gateway; /* Gateway IP address */ + +extern __be32 ic_servaddr; /* Boot server IP address */ + +extern __be32 root_server_addr; /* Address of NFS server */ +extern u8 root_server_path[]; /* Path to mount as root */ + + +/* bits in ic_proto_{enabled,used} */ +#define IC_PROTO 0xFF /* Protocols mask: */ +#define IC_BOOTP 0x01 /* BOOTP (or DHCP, see below) */ +#define IC_RARP 0x02 /* RARP */ +#define IC_USE_DHCP 0x100 /* If on, use DHCP instead of BOOTP */ -- cgit v1.3.1