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 --- scripts/timer_migration_tree.py | 122 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 122 insertions(+) create mode 100755 scripts/timer_migration_tree.py (limited to 'scripts/timer_migration_tree.py') diff --git a/scripts/timer_migration_tree.py b/scripts/timer_migration_tree.py new file mode 100755 index 000000000..faac9de85 --- /dev/null +++ b/scripts/timer_migration_tree.py @@ -0,0 +1,122 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0 + +""" +Draw the timer migration tree. + +1) Boot with trace_event==tmigr_connect_cpu_parent,tmigr_connect_child_parent +2) ./timer_migration_tree.py < /sys/kernel/tracing/trace +""" + +import re, sys +from ete3 import Tree + +class Node: + def __init__(self, group): + self.group = group + self.children = [] + self.parent = None + self.num_children = 0 + self.groupmask = 0 + self.lvl = -1 + + def set_groupmask(self, groupmask): + self.groupmask = groupmask + + def set_parent(self, parent): + self.parent = parent + + def add_child(self, child): + self.children.append(child) + + def set_lvl(self, lvl): + self.lvl = lvl + + def set_numa(self, numa): + self.numa = numa + + def set_num_children(self, num_children): + self.num_children = num_children + + def __repr__(self): + if self.parent: + parent_grp = self.parent.group + else: + parent_grp = "-" + return "Group: %s mask: %s parent: %s lvl: %d numa: %d num_children: %d" % (self.group, self.groupmask, parent_grp, self.lvl, self.numa, self.num_children) + +hierarchies = { } + +def get_hierarchy(capacity): + if capacity not in hierarchies: + hierarchies[capacity] = {} + return hierarchies[capacity] + +def get_node(capacity, group): + hier = get_hierarchy(capacity) + if group in hier: + return hier[group] + else: + n = Node(group) + hier[group] = n + return n + +def tmigr_connect_cpu_parent(ts, line): + s = re.search("tmigr_connect_cpu_parent: cpu=([0-9]+) groupmask=([0-9a-zA-Z]+) parent=([0-9a-zA-Z]+) lvl=([0-9]+) numa=([-]?[0-9]+) capacity=([-]?[0-9]+) num_children=([0-9]+)", line) + if s is None: + return False + (cpu, groupmask, parent, lvl, numa, capacity, num_children) = (int(s.group(1)), s.group(2), s.group(3), int(s.group(4)), int(s.group(5)), int(s.group(6)), int(s.group(7))) + n = get_node(capacity, cpu) + p = get_node(capacity, parent) + n.set_parent(p) + n.set_groupmask(groupmask) + n.set_lvl(-1) + p.set_lvl(lvl) + p.set_numa(numa) + n.set_numa(numa) + p.set_num_children(num_children) + p.add_child(n) + +def tmigr_connect_child_parent(ts, line): + s = re.search("tmigr_connect_child_parent: group=([0-9a-zA-Z]+) groupmask=([0-9a-zA-Z]+) parent=([0-9a-zA-Z]+) lvl=([0-9]+) numa=([-]?[0-9]+) capacity=([-]?[0-9]+) num_children=([0-9]+)", line) + if s is None: + return False + (group, groupmask, parent, lvl, numa, capacity, num_children) = (s.group(1), s.group(2), s.group(3), int(s.group(4)), int(s.group(5)), int(s.group(6)), int(s.group(7))) + n = get_node(capacity, group) + p = get_node(capacity, parent) + n.set_parent(p) + n.set_groupmask(groupmask) + p.set_lvl(lvl) + p.set_numa(numa) + p.set_num_children(num_children) + p.add_child(n) + +def populate(enode, node): + enode = enode.add_child(name = node.group) + enode.add_feature("groupmask", "m:%s" % node.groupmask) + enode.add_feature("lvl", "lvl:%d" % node.lvl) + enode.add_feature("numa", "node %d" % node.numa) + enode.add_feature("num_children", "c=%d" % node.num_children) + for child in node.children: + populate(enode, child) + +if __name__ == "__main__": + for line in sys.stdin: + s = re.search("([0-9]+[.][0-9]{6}): (.+?)$", line, re.S) + if s is not None: + if tmigr_connect_cpu_parent(float(s.group(1)), s.group(2)): + continue + if tmigr_connect_child_parent(float(s.group(1)), s.group(2)): + continue + + for cap in hierarchies: + h = hierarchies[cap] + print("Tree for capacity %d" % cap) + for k in h: + n = h[k] + while n.parent != None: + n = n.parent + root = Tree() + populate(root, n) + print(root.get_ascii(show_internal=True, attributes=["name", "numa", "lvl"])) + break -- cgit v1.3.1