From 4310c6b8e75d6a47f7548e5948fbe6318aa4440a Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Mon, 31 Aug 2026 10:58:09 +0300 Subject: thunderbolt: Fix NULL dereference in tb_remove_work() There is a slight race between tb_remove_work() and tb_domain_remove() which leads to dereferencing a NULL tb->root_switch pointer inside tb_free_unplugged_xdomains(): Thread A Thread B tb_remove_work() tb_domain_remove() mutex_lock(&tb->lock) tb_stop() /* doesn't cancel a running callback */ cancel_delayed_work(&tcm->remove_work) ... tb_switch_remove(tb->root_switch) tb->root_switch = NULL mutex_unlock(&tb->lock) mutex_lock(&tb->lock) ... /* without checking ->root_switch */ tb_free_unplugged_xdomains(tb->root_switch) mutex_unlock(&tb->lock) Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains() out of the &tb->lock section and the check for tb->root_switch, in particular. It states: For this reason separate removing the XDomain from the topology data structures (where we need the lock) from unregistering the device from the bus (where remove callbacks of the drivers are being called). tb_free_unplugged_xdomains() belongs to the former group of functions requiring the lock. And it also calls tb_xdomain_remove() which should only be called with &tb->lock held. Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool. Fixes: a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Signed-off-by: Mika Westerberg --- include/xen/interface/features.h | 102 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) create mode 100644 include/xen/interface/features.h (limited to 'include/xen/interface/features.h') diff --git a/include/xen/interface/features.h b/include/xen/interface/features.h new file mode 100644 index 000000000..53f760378 --- /dev/null +++ b/include/xen/interface/features.h @@ -0,0 +1,102 @@ +/* SPDX-License-Identifier: MIT */ +/****************************************************************************** + * features.h + * + * Feature flags, reported by XENVER_get_features. + * + * Copyright (c) 2006, Keir Fraser + */ + +#ifndef __XEN_PUBLIC_FEATURES_H__ +#define __XEN_PUBLIC_FEATURES_H__ + +/* + * If set, the guest does not need to write-protect its pagetables, and can + * update them via direct writes. + */ +#define XENFEAT_writable_page_tables 0 + +/* + * If set, the guest does not need to write-protect its segment descriptor + * tables, and can update them via direct writes. + */ +#define XENFEAT_writable_descriptor_tables 1 + +/* + * If set, translation between the guest's 'pseudo-physical' address space + * and the host's machine address space are handled by the hypervisor. In this + * mode the guest does not need to perform phys-to/from-machine translations + * when performing page table operations. + */ +#define XENFEAT_auto_translated_physmap 2 + +/* If set, the guest is running in supervisor mode (e.g., x86 ring 0). */ +#define XENFEAT_supervisor_mode_kernel 3 + +/* + * If set, the guest does not need to allocate x86 PAE page directories + * below 4GB. This flag is usually implied by auto_translated_physmap. + */ +#define XENFEAT_pae_pgdir_above_4gb 4 + +/* x86: Does this Xen host support the MMU_PT_UPDATE_PRESERVE_AD hypercall? */ +#define XENFEAT_mmu_pt_update_preserve_ad 5 + +/* x86: Does this Xen host support the MMU_{CLEAR,COPY}_PAGE hypercall? */ +#define XENFEAT_highmem_assist 6 + +/* + * If set, GNTTABOP_map_grant_ref honors flags to be placed into guest kernel + * available pte bits. + */ +#define XENFEAT_gnttab_map_avail_bits 7 + +/* x86: Does this Xen host support the HVM callback vector type? */ +#define XENFEAT_hvm_callback_vector 8 + +/* x86: pvclock algorithm is safe to use on HVM */ +#define XENFEAT_hvm_safe_pvclock 9 + +/* x86: pirq can be used by HVM guests */ +#define XENFEAT_hvm_pirqs 10 + +/* operation as Dom0 is supported */ +#define XENFEAT_dom0 11 + +/* Xen also maps grant references at pfn = mfn. + * This feature flag is deprecated and should not be used. +#define XENFEAT_grant_map_identity 12 + */ + +/* Guest can use XENMEMF_vnode to specify virtual node for memory op. */ +#define XENFEAT_memory_op_vnode_supported 13 + +/* arm: Hypervisor supports ARM SMC calling convention. */ +#define XENFEAT_ARM_SMCCC_supported 14 + +/* + * x86/PVH: If set, ACPI RSDP can be placed at any address. Otherwise RSDP + * must be located in lower 1MB, as required by ACPI Specification for IA-PC + * systems. + * This feature flag is only consulted if XEN_ELFNOTE_GUEST_OS contains + * the "linux" string. + */ +#define XENFEAT_linux_rsdp_unrestricted 15 + +/* + * A direct-mapped (or 1:1 mapped) domain is a domain for which its + * local pages have gfn == mfn. If a domain is direct-mapped, + * XENFEAT_direct_mapped is set; otherwise XENFEAT_not_direct_mapped + * is set. + * + * If neither flag is set (e.g. older Xen releases) the assumptions are: + * - not auto_translated domains (x86 only) are always direct-mapped + * - on x86, auto_translated domains are not direct-mapped + * - on ARM, Dom0 is direct-mapped, DomUs are not + */ +#define XENFEAT_not_direct_mapped 16 +#define XENFEAT_direct_mapped 17 + +#define XENFEAT_NR_SUBMAPS 1 + +#endif /* __XEN_PUBLIC_FEATURES_H__ */ -- cgit v1.3.1