thunderbolt: Fix NULL dereference in tb_remove_work()grafted

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 <pchelkin@ispras.ru>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

1 files changed, 212 insertions, 0 deletions

diff --git a/scripts/setlocalversion b/scripts/setlocalversion
new file mode 100755
index 000000000..28169d7e1
--- /dev/null
+++ b/scripts/setlocalversion
@@ -0,0 +1,212 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# This scripts adds local version information from the version
+# control system git.
+#
+# If something goes wrong, send a mail the kernel build mailinglist
+# (see MAINTAINERS) and CC Nico Schottelius
+# <nico-linuxsetlocalversion -at- schottelius.org>.
+#
+#
+
+set -e
+
+usage() {
+	echo "Usage: $0 [--no-local] [srctree]" >&2
+	exit 1
+}
+
+no_local=false
+if test "$1" = "--no-local"; then
+	no_local=true
+	shift
+fi
+
+srctree=.
+if test $# -gt 0; then
+	srctree=$1
+	shift
+fi
+if test $# -gt 0 -o ! -d "$srctree"; then
+	usage
+fi
+
+try_tag() {
+	tag="$1"
+
+	# Is $tag an annotated tag?
+	if [ "$(git cat-file -t "$tag" 2> /dev/null)" != tag ]; then
+		 return
+	fi
+
+	# Is it an ancestor of HEAD, and if so, how many commits are in $tag..HEAD?
+	# shellcheck disable=SC2046 # word splitting is the point here
+	set -- $(git rev-list --count --left-right "$tag"...HEAD 2> /dev/null)
+
+	# $1 is 0 if and only if $tag is an ancestor of HEAD. Use
+	# string comparison, because $1 is empty if the 'git rev-list'
+	# command somehow failed.
+	if [ "$1" != 0 ]; then
+		return
+	fi
+
+	# $2 is the number of commits in the range $tag..HEAD, possibly 0.
+	count="$2"
+}
+
+scm_version()
+{
+	local short=false
+	local no_dirty=false
+	local tag
+
+	while [ $# -gt 0 ];
+	do
+		case "$1" in
+		--short)
+			short=true;;
+		--no-dirty)
+			no_dirty=true;;
+		esac
+		shift
+	done
+
+	cd "$srctree"
+
+	if test -n "$(git rev-parse --show-cdup 2>/dev/null)"; then
+		return
+	fi
+
+	if ! head=$(git rev-parse --verify HEAD 2>/dev/null); then
+		return
+	fi
+
+	# mainline kernel:  6.2.0-rc5  ->  v6.2-rc5
+	# stable kernel:    6.1.7      ->  v6.1.7
+	version_tag=v$(echo "${KERNELVERSION}" | sed -E 's/^([0-9]+\.[0-9]+)\.0(.*)$/\1\2/')
+
+	# try_tag initializes count if the tag is usable.
+	count=
+
+	# If a localversion* file exists, and the corresponding
+	# annotated tag exists and is an ancestor of HEAD, use
+	# it. This is the case in linux-next.
+	if [ -n "${file_localversion#-}" ] ; then
+		try_tag "${file_localversion#-}"
+	fi
+
+	# Otherwise, if a localversion* file exists, and the tag
+	# obtained by appending it to the tag derived from
+	# KERNELVERSION exists and is an ancestor of HEAD, use
+	# it. This is e.g. the case in linux-rt.
+	if [ -z "${count}" ] && [ -n "${file_localversion}" ]; then
+		try_tag "${version_tag}${file_localversion}"
+	fi
+
+	# Otherwise, default to the annotated tag derived from KERNELVERSION.
+	if [ -z "${count}" ]; then
+		try_tag "${version_tag}"
+	fi
+
+	# If we are at the tagged commit, we ignore it because the
+	# version is well-defined. If none of the attempted tags exist
+	# or were usable, $count is still empty.
+	if [ -z "${count}" ] || [ "${count}" -gt 0 ]; then
+
+		# If only the short version is requested, don't bother
+		# running further git commands
+		if $short; then
+			echo "+"
+			return
+		fi
+
+		# If we are past the tagged commit, we pretty print it.
+		# (like 6.1.0-14595-g292a089d78d3)
+		if [ -n "${count}" ]; then
+			printf "%s%05d" "-" "${count}"
+		fi
+
+		# Add -g and exactly 12 hex chars.
+		printf '%s%.12s' -g "$head"
+	fi
+
+	if ${no_dirty}; then
+		return
+	fi
+
+	# Check for uncommitted changes.
+	# This script must avoid any write attempt to the source tree, which
+	# might be read-only.
+	# You cannot use 'git describe --dirty' because it tries to create
+	# .git/index.lock .
+	# First, with git-status, but --no-optional-locks is only supported in
+	# git >= 2.14, so fall back to git-diff-index if it fails. Note that
+	# git-diff-index does not refresh the index, so it may give misleading
+	# results.
+	# See git-update-index(1), git-diff-index(1), and git-status(1).
+	if {
+		git --no-optional-locks status -uno --porcelain 2>/dev/null ||
+		git diff-index --name-only HEAD
+	} | read dummy; then
+		printf '%s' -dirty
+	fi
+}
+
+collect_files()
+{
+	local file res=
+
+	for file; do
+		case "$file" in
+		*\~*)
+			continue
+			;;
+		esac
+		if test -e "$file"; then
+			res="$res$(cat "$file")"
+		fi
+	done
+	echo "$res"
+}
+
+if [ -z "${KERNELVERSION}" ]; then
+	echo "KERNELVERSION is not set" >&2
+	exit 1
+fi
+
+# localversion* files in the build and source directory
+file_localversion="$(collect_files localversion*)"
+if test ! "$srctree" -ef .; then
+	file_localversion="${file_localversion}$(collect_files "$srctree"/localversion*)"
+fi
+
+if ${no_local}; then
+	echo "${KERNELVERSION}$(scm_version --no-dirty)"
+	exit 0
+fi
+
+if ! test -e include/config/auto.conf; then
+	echo "Error: kernelrelease not valid - run 'make prepare' to update it" >&2
+	exit 1
+fi
+
+# version string from CONFIG_LOCALVERSION
+config_localversion=$(sed -n 's/^CONFIG_LOCALVERSION=\(.*\)$/\1/p' include/config/auto.conf)
+
+# scm version string if not at the kernel version tag or at the file_localversion
+if grep -q "^CONFIG_LOCALVERSION_AUTO=y$" include/config/auto.conf; then
+	# full scm version string
+	scm_version="$(scm_version)"
+elif [ "${LOCALVERSION+set}" != "set" ]; then
+	# If the variable LOCALVERSION is not set, append a plus
+	# sign if the repository is not in a clean annotated or
+	# signed tagged state (as git describe only looks at signed
+	# or annotated tags - git tag -a/-s).
+	#
+	# If the variable LOCALVERSION is set (including being set
+	# to an empty string), we don't want to append a plus sign.
+	scm_version="$(scm_version --short)"
+fi
+
+echo "${KERNELVERSION}${file_localversion}${config_localversion}${LOCALVERSION}${scm_version}"