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, 437 insertions, 0 deletions

diff --git a/scripts/dtc/treesource.c b/scripts/dtc/treesource.c
new file mode 100644
index 000000000..bf648bf6c
--- /dev/null
+++ b/scripts/dtc/treesource.c
@@ -0,0 +1,437 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * (C) Copyright David Gibson <dwg@au1.ibm.com>, IBM Corporation.  2005.
+ */
+
+#include "dtc.h"
+#include "srcpos.h"
+
+extern FILE *yyin;
+extern int yyparse(void);
+extern YYLTYPE yylloc;
+
+struct dt_info *parser_output;
+bool treesource_error;
+
+struct dt_info *dt_from_source(const char *fname)
+{
+	parser_output = NULL;
+	treesource_error = false;
+
+	srcfile_push(fname);
+	yyin = current_srcfile->f;
+	yylloc.file = current_srcfile;
+
+	if (yyparse() != 0)
+		die("Unable to parse input tree\n");
+
+	if (treesource_error)
+		die("Syntax error parsing input tree\n");
+
+	return parser_output;
+}
+
+static void write_prefix(FILE *f, int level)
+{
+	int i;
+
+	for (i = 0; i < level; i++)
+		fputc('\t', f);
+}
+
+static bool isstring(char c)
+{
+	return (isprint((unsigned char)c)
+		|| (c == '\0')
+		|| strchr("\a\b\t\n\v\f\r", c));
+}
+
+static void write_propval_string(FILE *f, const char *s, size_t len)
+{
+	const char *end = s + len - 1;
+
+	if (!len)
+		return;
+
+	assert(*end == '\0');
+
+	fprintf(f, "\"");
+	while (s < end) {
+		char c = *s++;
+		switch (c) {
+		case '\a':
+			fprintf(f, "\\a");
+			break;
+		case '\b':
+			fprintf(f, "\\b");
+			break;
+		case '\t':
+			fprintf(f, "\\t");
+			break;
+		case '\n':
+			fprintf(f, "\\n");
+			break;
+		case '\v':
+			fprintf(f, "\\v");
+			break;
+		case '\f':
+			fprintf(f, "\\f");
+			break;
+		case '\r':
+			fprintf(f, "\\r");
+			break;
+		case '\\':
+			fprintf(f, "\\\\");
+			break;
+		case '\"':
+			fprintf(f, "\\\"");
+			break;
+		case '\0':
+			fprintf(f, "\\0");
+			break;
+		default:
+			if (isprint((unsigned char)c))
+				fprintf(f, "%c", c);
+			else
+				fprintf(f, "\\x%02"PRIx8, c);
+		}
+	}
+	fprintf(f, "\"");
+}
+
+static void write_propval_int(FILE *f, const char *p, size_t len, size_t width)
+{
+	const char *end = p + len;
+	assert(len % width == 0);
+
+	for (; p < end; p += width) {
+		switch (width) {
+		case 1:
+			fprintf(f, "%02"PRIx8, *(const uint8_t*)p);
+			break;
+		case 2:
+			fprintf(f, "0x%02"PRIx16, dtb_ld16(p));
+			break;
+		case 4:
+			fprintf(f, "0x%02"PRIx32, dtb_ld32(p));
+			break;
+		case 8:
+			fprintf(f, "0x%02"PRIx64, dtb_ld64(p));
+			break;
+		}
+		if (p + width < end)
+			fputc(' ', f);
+	}
+}
+
+static const char *delim_start[] = {
+	[TYPE_UINT8] = "[",
+	[TYPE_UINT16] = "/bits/ 16 <",
+	[TYPE_UINT32] = "<",
+	[TYPE_UINT64] = "/bits/ 64 <",
+	[TYPE_STRING] = "",
+};
+static const char *delim_end[] = {
+	[TYPE_UINT8] = "]",
+	[TYPE_UINT16] = ">",
+	[TYPE_UINT32] = ">",
+	[TYPE_UINT64] = ">",
+	[TYPE_STRING] = "",
+};
+
+/*
+ * The invariants in the marker list are:
+ *  - offsets are non-strictly monotonically increasing
+ *  - for a single offset there is at most one type marker
+ *  - for a single offset that has both a type marker and non-type markers, the
+ *    type marker appears before the others.
+ */
+static struct marker **add_marker(struct marker **mi,
+				  enum markertype type, unsigned int offset, char *ref)
+{
+	struct marker *nm;
+
+	while (*mi && (*mi)->offset < offset)
+		mi = &(*mi)->next;
+
+	if (*mi && (*mi)->offset == offset && is_type_marker((*mi)->type)) {
+		if (is_type_marker(type))
+			return mi;
+		mi = &(*mi)->next;
+	}
+
+	if (*mi && (*mi)->offset == offset && type == (*mi)->type)
+		return mi;
+
+	nm = xmalloc(sizeof(*nm));
+	nm->type = type;
+	nm->offset = offset;
+	nm->ref = ref;
+	nm->next = *mi;
+	*mi = nm;
+
+	return &nm->next;
+}
+
+void property_add_marker(struct property *prop,
+			 enum markertype type, unsigned int offset, char *ref)
+{
+	add_marker(&prop->val.markers, type, offset, ref);
+}
+
+static void add_string_markers(struct property *prop, unsigned int offset, int len)
+{
+	int l;
+	const char *p = prop->val.val + offset;
+	struct marker **mi = &prop->val.markers;
+
+	for (l = strlen(p) + 1; l < len; l += strlen(p + l) + 1)
+		mi = add_marker(mi, TYPE_STRING, offset + l, NULL);
+}
+
+void add_phandle_marker(struct dt_info *dti, struct property *prop, unsigned int offset)
+{
+	cell_t phandle;
+	struct node *refn;
+	char *ref;
+
+	if (prop->val.len < offset + 4) {
+		if (quiet < 1)
+			fprintf(stderr,
+				"Warning: property %s too short to contain a phandle at offset %u\n",
+				prop->name, offset);
+		return;
+	}
+
+	phandle = dtb_ld32(prop->val.val + offset);
+	refn = get_node_by_phandle(dti->dt, phandle);
+
+	if (!refn) {
+		if (quiet < 1)
+			fprintf(stderr,
+				"Warning: node referenced by phandle 0x%x in property %s not found\n",
+				phandle, prop->name);
+		return;
+	}
+
+	if (refn->labels)
+		ref = refn->labels->label;
+	else
+		ref = refn->fullpath;
+
+	add_marker(&prop->val.markers, REF_PHANDLE, offset, ref);
+}
+
+static enum markertype guess_value_type(struct property *prop, unsigned int offset, int len)
+{
+	const char *p = prop->val.val + offset;
+	int nnotstring = 0, nnul = 0;
+	int i;
+
+	for (i = 0; i < len; i++) {
+		if (! isstring(p[i]))
+			nnotstring++;
+		if (p[i] == '\0')
+			nnul++;
+	}
+
+	if ((p[len-1] == '\0') && (nnotstring == 0) && (nnul <= len - nnul)) {
+		if (nnul > 1)
+			add_string_markers(prop, offset, len);
+		return TYPE_STRING;
+	} else if ((len % sizeof(cell_t)) == 0) {
+		return TYPE_UINT32;
+	}
+
+	return TYPE_UINT8;
+}
+
+static void guess_type_markers(struct property *prop)
+{
+	struct marker **m = &prop->val.markers;
+	unsigned int offset = 0;
+
+	for (m = &prop->val.markers; *m; m = &((*m)->next)) {
+		if (is_type_marker((*m)->type))
+			/* assume the whole property is already marked */
+			return;
+
+		if ((*m)->offset > offset) {
+			m = add_marker(m, guess_value_type(prop, offset, (*m)->offset - offset),
+				       offset, NULL);
+
+			offset = (*m)->offset;
+		}
+
+		if ((*m)->type == REF_PHANDLE) {
+			m = add_marker(m, TYPE_UINT32, offset, NULL);
+			offset += 4;
+		}
+	}
+
+	if (offset < prop->val.len)
+		add_marker(m, guess_value_type(prop, offset, prop->val.len - offset),
+			   offset, NULL);
+}
+
+static void write_propval(FILE *f, struct property *prop)
+{
+	size_t len = prop->val.len;
+	struct marker *m;
+	enum markertype emit_type = TYPE_NONE;
+	char *srcstr;
+
+	if (len == 0) {
+		fprintf(f, ";");
+		if (annotate) {
+			srcstr = srcpos_string_first(prop->srcpos, annotate);
+			if (srcstr) {
+				fprintf(f, " /* %s */", srcstr);
+				free(srcstr);
+			}
+		}
+		fprintf(f, "\n");
+		return;
+	}
+
+	fprintf(f, " =");
+
+	guess_type_markers(prop);
+	m = prop->val.markers;
+
+	for_each_marker(m) {
+		size_t chunk_len = (m->next ? m->next->offset : len) - m->offset;
+		size_t data_len = type_marker_length(m) ? : len - m->offset;
+		const char *p = &prop->val.val[m->offset];
+		struct marker *m_phandle;
+
+		if (is_type_marker(m->type)) {
+			emit_type = m->type;
+			fprintf(f, " %s", delim_start[emit_type]);
+		} else if (m->type == LABEL)
+			fprintf(f, " %s:", m->ref);
+
+		if (emit_type == TYPE_NONE || chunk_len == 0)
+			continue;
+
+		switch(emit_type) {
+		case TYPE_UINT16:
+			write_propval_int(f, p, chunk_len, 2);
+			break;
+		case TYPE_UINT32:
+			m_phandle = prop->val.markers;
+			for_each_marker_of_type(m_phandle, REF_PHANDLE)
+				if (m->offset == m_phandle->offset)
+					break;
+
+			if (m_phandle) {
+				if (m_phandle->ref[0] == '/')
+					fprintf(f, "&{%s}", m_phandle->ref);
+				else
+					fprintf(f, "&%s", m_phandle->ref);
+				if (chunk_len > 4) {
+					fputc(' ', f);
+					write_propval_int(f, p + 4, chunk_len - 4, 4);
+				}
+			} else {
+				write_propval_int(f, p, chunk_len, 4);
+			}
+			if (data_len > chunk_len)
+				fputc(' ', f);
+			break;
+		case TYPE_UINT64:
+			write_propval_int(f, p, chunk_len, 8);
+			break;
+		case TYPE_STRING:
+			write_propval_string(f, p, chunk_len);
+			break;
+		default:
+			write_propval_int(f, p, chunk_len, 1);
+		}
+
+		if (chunk_len == data_len) {
+			size_t pos = m->offset + chunk_len;
+			fprintf(f, pos == len ? "%s" : "%s,",
+			        delim_end[emit_type] ? : "");
+			emit_type = TYPE_NONE;
+		}
+	}
+	fprintf(f, ";");
+	if (annotate) {
+		srcstr = srcpos_string_first(prop->srcpos, annotate);
+		if (srcstr) {
+			fprintf(f, " /* %s */", srcstr);
+			free(srcstr);
+		}
+	}
+	fprintf(f, "\n");
+}
+
+static void write_tree_source_node(FILE *f, struct node *tree, int level)
+{
+	struct property *prop;
+	struct node *child;
+	struct label *l;
+	char *srcstr;
+
+	write_prefix(f, level);
+	for_each_label(tree->labels, l)
+		fprintf(f, "%s: ", l->label);
+	if (tree->name && (*tree->name))
+		fprintf(f, "%s {", tree->name);
+	else
+		fprintf(f, "/ {");
+
+	if (annotate) {
+		srcstr = srcpos_string_first(tree->srcpos, annotate);
+		if (srcstr) {
+			fprintf(f, " /* %s */", srcstr);
+			free(srcstr);
+		}
+	}
+	fprintf(f, "\n");
+
+	for_each_property(tree, prop) {
+		write_prefix(f, level+1);
+		for_each_label(prop->labels, l)
+			fprintf(f, "%s: ", l->label);
+		fprintf(f, "%s", prop->name);
+		write_propval(f, prop);
+	}
+	for_each_child(tree, child) {
+		fprintf(f, "\n");
+		write_tree_source_node(f, child, level+1);
+	}
+	write_prefix(f, level);
+	fprintf(f, "};");
+	if (annotate) {
+		srcstr = srcpos_string_last(tree->srcpos, annotate);
+		if (srcstr) {
+			fprintf(f, " /* %s */", srcstr);
+			free(srcstr);
+		}
+	}
+	fprintf(f, "\n");
+}
+
+void dt_to_source(FILE *f, struct dt_info *dti)
+{
+	struct reserve_info *re;
+
+	fprintf(f, "/dts-v1/;\n");
+	if (dti->dtsflags & DTSF_PLUGIN)
+		fprintf(f, "/plugin/;\n");
+	fprintf(f, "\n");
+
+	for (re = dti->reservelist; re; re = re->next) {
+		struct label *l;
+
+		for_each_label(re->labels, l)
+			fprintf(f, "%s: ", l->label);
+		fprintf(f, "/memreserve/\t0x%016llx 0x%016llx;\n",
+			(unsigned long long)re->address,
+			(unsigned long long)re->size);
+	}
+
+	write_tree_source_node(f, dti->dt, 0);
+}