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/sctp/ulpqueue.h | 68 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 include/net/sctp/ulpqueue.h (limited to 'include/net/sctp/ulpqueue.h') diff --git a/include/net/sctp/ulpqueue.h b/include/net/sctp/ulpqueue.h new file mode 100644 index 000000000..60f664129 --- /dev/null +++ b/include/net/sctp/ulpqueue.h @@ -0,0 +1,68 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* SCTP kernel implementation + * (C) Copyright IBM Corp. 2001, 2004 + * Copyright (c) 1999-2000 Cisco, Inc. + * Copyright (c) 1999-2001 Motorola, Inc. + * Copyright (c) 2001 Intel Corp. + * Copyright (c) 2001 Nokia, Inc. + * Copyright (c) 2001 La Monte H.P. Yarroll + * + * These are the definitions needed for the sctp_ulpq type. The + * sctp_ulpq is the interface between the Upper Layer Protocol, or ULP, + * and the core SCTP state machine. This is the component which handles + * reassembly and ordering. + * + * Please send any bug reports or fixes you make to the + * email addresses: + * lksctp developers + * + * Written or modified by: + * Jon Grimm + * La Monte H.P. Yarroll + * Sridhar Samudrala + */ + +#ifndef __sctp_ulpqueue_h__ +#define __sctp_ulpqueue_h__ + +/* A structure to carry information to the ULP (e.g. Sockets API) */ +struct sctp_ulpq { + char pd_mode; + struct sctp_association *asoc; + struct sk_buff_head reasm; + struct sk_buff_head reasm_uo; + struct sk_buff_head lobby; +}; + +/* Prototypes. */ +void sctp_ulpq_init(struct sctp_ulpq *ulpq, struct sctp_association *asoc); +void sctp_ulpq_flush(struct sctp_ulpq *ulpq); +void sctp_ulpq_free(struct sctp_ulpq *); + +/* Add a new DATA chunk for processing. */ +int sctp_ulpq_tail_data(struct sctp_ulpq *, struct sctp_chunk *, gfp_t); + +/* Add a new event for propagation to the ULP. */ +int sctp_ulpq_tail_event(struct sctp_ulpq *, struct sk_buff_head *skb_list); + +/* Renege previously received chunks. */ +void sctp_ulpq_renege(struct sctp_ulpq *, struct sctp_chunk *, gfp_t); + +/* Perform partial delivery. */ +void sctp_ulpq_partial_delivery(struct sctp_ulpq *, gfp_t); + +/* Abort the partial delivery. */ +void sctp_ulpq_abort_pd(struct sctp_ulpq *, gfp_t); + +/* Clear the partial data delivery condition on this socket. */ +int sctp_clear_pd(struct sock *sk, struct sctp_association *asoc); + +/* Skip over an SSN. */ +void sctp_ulpq_skip(struct sctp_ulpq *ulpq, __u16 sid, __u16 ssn); + +void sctp_ulpq_reasm_flushtsn(struct sctp_ulpq *, __u32); + +__u16 sctp_ulpq_renege_list(struct sctp_ulpq *ulpq, + struct sk_buff_head *list, __u16 needed); + +#endif /* __sctp_ulpqueue_h__ */ -- cgit v1.3.1