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-rw-r--r--src/bplist.c112
1 files changed, 68 insertions, 44 deletions
diff --git a/src/bplist.c b/src/bplist.c
index 74348b8..0591526 100644
--- a/src/bplist.c
+++ b/src/bplist.c
@@ -243,6 +243,37 @@ struct bplist_data {
plist_err_t err;
};
+/*
+ * Check that len bytes starting at ptr lie within the object area of the
+ * binary plist, i.e. between the start of the data and the offset table.
+ * The check compares lengths instead of computing ptr + len, so it never
+ * forms a pointer outside of the input buffer and cannot wrap around.
+ */
+static int bplist_object_range_valid(const struct bplist_data *bplist, const char *ptr, uint64_t len)
+{
+ if (ptr < bplist->data || ptr > bplist->offset_table) {
+ return 0;
+ }
+ return len <= (uint64_t)(bplist->offset_table - ptr);
+}
+
+/*
+ * Read the object reference at position ref_index of the reference list
+ * that starts at refs. The offset is computed with overflow checking and
+ * validated before the reference is read.
+ */
+static int bplist_read_object_ref(const struct bplist_data *bplist, const char *refs, uint64_t ref_index, uint64_t *ref)
+{
+ uint64_t ref_offset = 0;
+ if (uint64_mul_overflow(ref_index, bplist->ref_size, &ref_offset) ||
+ ref_offset > UINT64_MAX - bplist->ref_size ||
+ !bplist_object_range_valid(bplist, refs, ref_offset + bplist->ref_size)) {
+ return 0;
+ }
+ *ref = UINT_TO_HOST(refs + ref_offset, bplist->ref_size);
+ return 1;
+}
+
#ifdef DEBUG
static int plist_bin_debug = 0;
#define PLIST_BIN_ERR(...) if (plist_bin_debug) { fprintf(stderr, "libplist[binparser] ERROR: " __VA_ARGS__); }
@@ -517,15 +548,12 @@ static plist_t parse_data_node(const char **bnode, uint64_t size)
static plist_t parse_dict_node(struct bplist_data *bplist, const char** bnode, uint64_t size)
{
uint64_t j;
- uint64_t str_i = 0, str_j = 0;
uint64_t index1, index2;
plist_data_t data = plist_new_plist_data();
if (!data) {
PLIST_BIN_ERR("%s: failed to allocate plist data\n", __func__);
return NULL;
}
- const char *index1_ptr = NULL;
- const char *index2_ptr = NULL;
data->type = PLIST_DICT;
data->length = size;
@@ -538,21 +566,14 @@ static plist_t parse_dict_node(struct bplist_data *bplist, const char** bnode, u
}
for (j = 0; j < data->length; j++) {
- str_i = j * bplist->ref_size;
- str_j = (j + size) * bplist->ref_size;
- index1_ptr = (*bnode) + str_i;
- index2_ptr = (*bnode) + str_j;
-
- if ((index1_ptr < bplist->data || index1_ptr + bplist->ref_size > bplist->offset_table) ||
- (index2_ptr < bplist->data || index2_ptr + bplist->ref_size > bplist->offset_table)) {
+ /* key references come first, followed by all value references */
+ if (!bplist_read_object_ref(bplist, *bnode, j, &index1) ||
+ !bplist_read_object_ref(bplist, *bnode, j + size, &index2)) {
plist_free(node);
PLIST_BIN_ERR("%s: dict entry %" PRIu64 " is outside of valid range\n", __func__, j);
return NULL;
}
- index1 = UINT_TO_HOST(index1_ptr, bplist->ref_size);
- index2 = UINT_TO_HOST(index2_ptr, bplist->ref_size);
-
if (index1 >= bplist->num_objects) {
plist_free(node);
PLIST_BIN_ERR("%s: dict entry %" PRIu64 ": key index (%" PRIu64 ") must be smaller than the number of objects (%" PRIu64 ")\n", __func__, j, index1, bplist->num_objects);
@@ -614,14 +635,12 @@ static plist_t parse_dict_node(struct bplist_data *bplist, const char** bnode, u
static plist_t parse_array_node(struct bplist_data *bplist, const char** bnode, uint64_t size)
{
uint64_t j;
- uint64_t str_j = 0;
uint64_t index1;
plist_data_t data = plist_new_plist_data();
if (!data) {
PLIST_BIN_ERR("%s: failed to allocate plist data\n", __func__);
return NULL;
}
- const char *index1_ptr = NULL;
data->type = PLIST_ARRAY;
data->length = size;
@@ -634,17 +653,12 @@ static plist_t parse_array_node(struct bplist_data *bplist, const char** bnode,
}
for (j = 0; j < data->length; j++) {
- str_j = j * bplist->ref_size;
- index1_ptr = (*bnode) + str_j;
-
- if (index1_ptr < bplist->data || index1_ptr + bplist->ref_size > bplist->offset_table) {
+ if (!bplist_read_object_ref(bplist, *bnode, j, &index1)) {
plist_free(node);
PLIST_BIN_ERR("%s: array item %" PRIu64 " is outside of valid range\n", __func__, j);
return NULL;
}
- index1 = UINT_TO_HOST(index1_ptr, bplist->ref_size);
-
if (index1 >= bplist->num_objects) {
plist_free(node);
PLIST_BIN_ERR("%s: array item %" PRIu64 " object index (%" PRIu64 ") must be smaller than the number of objects (%" PRIu64 ")\n", __func__, j, index1, bplist->num_objects);
@@ -694,12 +708,16 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
{
uint16_t type = 0;
uint64_t size = 0;
- uint64_t pobject = 0;
- uint64_t poffset_table = (uint64_t)(uintptr_t)bplist->offset_table;
+ uint64_t data_size = 0;
if (!object)
return NULL;
+ if (!bplist_object_range_valid(bplist, *object, 1)) {
+ PLIST_BIN_ERR("%s: node marker points outside of valid range\n", __func__);
+ return NULL;
+ }
+
type = (**object) & BPLIST_MASK;
size = (**object) & BPLIST_FILL;
(*object)++;
@@ -713,6 +731,10 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
case BPLIST_SET:
case BPLIST_DICT:
{
+ if (!bplist_object_range_valid(bplist, *object, 1)) {
+ PLIST_BIN_ERR("%s: size node for node type 0x%02x points outside of valid range\n", __func__, type);
+ return NULL;
+ }
uint16_t next_size = **object & BPLIST_FILL;
if ((**object & BPLIST_MASK) != BPLIST_INT) {
PLIST_BIN_ERR("%s: invalid size node type for node type 0x%02x: found 0x%02x, expected 0x%02x\n", __func__, type, **object & BPLIST_MASK, BPLIST_INT);
@@ -720,7 +742,7 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
}
(*object)++;
next_size = 1 << next_size;
- if (*object + next_size > bplist->offset_table) {
+ if (!bplist_object_range_valid(bplist, *object, next_size)) {
PLIST_BIN_ERR("%s: size node data bytes for node type 0x%02x point outside of valid range\n", __func__, type);
return NULL;
}
@@ -733,8 +755,6 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
}
}
- pobject = (uint64_t)(uintptr_t)*object;
-
switch (type)
{
@@ -785,14 +805,14 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
}
case BPLIST_INT:
- if (pobject + (uint64_t)(1 << size) > poffset_table) {
+ if (!bplist_object_range_valid(bplist, *object, (uint64_t)1 << size)) {
PLIST_BIN_ERR("%s: BPLIST_INT data bytes point outside of valid range\n", __func__);
return NULL;
}
return parse_int_node(object, size);
case BPLIST_REAL:
- if (pobject + (uint64_t)(1 << size) > poffset_table) {
+ if (!bplist_object_range_valid(bplist, *object, (uint64_t)1 << size)) {
PLIST_BIN_ERR("%s: BPLIST_REAL data bytes point outside of valid range\n", __func__);
return NULL;
}
@@ -803,32 +823,32 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
PLIST_BIN_ERR("%s: invalid data size for BPLIST_DATE node\n", __func__);
return NULL;
}
- if (pobject + (uint64_t)(1 << size) > poffset_table) {
+ if (!bplist_object_range_valid(bplist, *object, (uint64_t)1 << size)) {
PLIST_BIN_ERR("%s: BPLIST_DATE data bytes point outside of valid range\n", __func__);
return NULL;
}
return parse_date_node(object, size);
case BPLIST_DATA:
- if (pobject + size < pobject || pobject + size > poffset_table) {
+ if (!bplist_object_range_valid(bplist, *object, size)) {
PLIST_BIN_ERR("%s: BPLIST_DATA data bytes point outside of valid range\n", __func__);
return NULL;
}
return parse_data_node(object, size);
case BPLIST_STRING:
- if (pobject + size < pobject || pobject + size > poffset_table) {
+ if (!bplist_object_range_valid(bplist, *object, size)) {
PLIST_BIN_ERR("%s: BPLIST_STRING data bytes point outside of valid range\n", __func__);
return NULL;
}
return parse_string_node(object, size);
case BPLIST_UNICODE:
- if (size*2 < size) {
+ if (uint64_mul_overflow(size, sizeof(uint16_t), &data_size)) {
PLIST_BIN_ERR("%s: Integer overflow when calculating BPLIST_UNICODE data size.\n", __func__);
return NULL;
}
- if (pobject + size*2 < pobject || pobject + size*2 > poffset_table) {
+ if (!bplist_object_range_valid(bplist, *object, data_size)) {
PLIST_BIN_ERR("%s: BPLIST_UNICODE data bytes point outside of valid range\n", __func__);
return NULL;
}
@@ -836,21 +856,25 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
case BPLIST_SET:
case BPLIST_ARRAY:
- if (pobject + size < pobject || pobject + size > poffset_table) {
+ /* one object reference per item */
+ if (uint64_mul_overflow(size, bplist->ref_size, &data_size) ||
+ !bplist_object_range_valid(bplist, *object, data_size)) {
PLIST_BIN_ERR("%s: BPLIST_ARRAY data bytes point outside of valid range\n", __func__);
return NULL;
}
return parse_array_node(bplist, object, size);
case BPLIST_UID:
- if (pobject + size+1 > poffset_table) {
+ if (!bplist_object_range_valid(bplist, *object, size + 1)) {
PLIST_BIN_ERR("%s: BPLIST_UID data bytes point outside of valid range\n", __func__);
return NULL;
}
return parse_uid_node(object, size);
case BPLIST_DICT:
- if (pobject + size < pobject || pobject + size > poffset_table) {
+ /* one key and one value reference per entry */
+ if (uint64_mul_overflow(size, 2 * (uint64_t)bplist->ref_size, &data_size) ||
+ !bplist_object_range_valid(bplist, *object, data_size)) {
PLIST_BIN_ERR("%s: BPLIST_DICT data bytes point outside of valid range\n", __func__);
return NULL;
}
@@ -876,13 +900,14 @@ static plist_t parse_bin_node_at_index(struct bplist_data *bplist, uint32_t node
return NULL;
}
- idx_ptr = bplist->offset_table + node_index * bplist->offset_size;
- if (idx_ptr < bplist->offset_table ||
- idx_ptr >= bplist->offset_table + bplist->num_objects * bplist->offset_size) {
+ /* num_objects * offset_size was checked against the input size in plist_from_bin() */
+ uint64_t idx_offset = (uint64_t)node_index * bplist->offset_size;
+ if (idx_offset >= bplist->num_objects * bplist->offset_size) {
PLIST_BIN_ERR("node index %u points outside of valid range\n", node_index);
bplist->err = PLIST_ERR_PARSE;
return NULL;
}
+ idx_ptr = bplist->offset_table + idx_offset;
uint64_t node_offset = UINT_TO_HOST(idx_ptr, bplist->offset_size);
if (node_offset > (uint64_t)bplist->size) {
@@ -890,13 +915,14 @@ static plist_t parse_bin_node_at_index(struct bplist_data *bplist, uint32_t node
bplist->err = PLIST_ERR_PARSE;
return NULL;
}
- ptr = bplist->data + node_offset;
/* make sure the node offset is in a sane range */
- if ((ptr < bplist->data+BPLIST_MAGIC_SIZE+BPLIST_VERSION_SIZE) || (ptr >= bplist->offset_table)) {
+ if (node_offset < BPLIST_MAGIC_SIZE + BPLIST_VERSION_SIZE ||
+ node_offset >= (uint64_t)(bplist->offset_table - bplist->data)) {
PLIST_BIN_ERR("offset for node index %u points outside of valid range\n", node_index);
bplist->err = PLIST_ERR_PARSE;
return NULL;
}
+ ptr = bplist->data + node_offset;
/* Objects can be referenced multiple times, so limit the total number of
nodes created to avoid excessive memory use from reference expansion. */
@@ -954,7 +980,6 @@ plist_err_t plist_from_bin(const char *plist_bin, uint32_t length, plist_t * pli
uint64_t root_object = 0;
const char *offset_table = NULL;
uint64_t offset_table_size = 0;
- const char *start_data = NULL;
const char *end_data = NULL;
if (!plist) {
@@ -981,7 +1006,6 @@ plist_err_t plist_from_bin(const char *plist_bin, uint32_t length, plist_t * pli
return PLIST_ERR_PARSE;
}
- start_data = plist_bin + BPLIST_MAGIC_SIZE + BPLIST_VERSION_SIZE;
end_data = plist_bin + length - sizeof(bplist_trailer_t);
//now parse trailer
@@ -1020,7 +1044,7 @@ plist_err_t plist_from_bin(const char *plist_bin, uint32_t length, plist_t * pli
return PLIST_ERR_PARSE;
}
- if (offset_table < start_data || offset_table >= end_data) {
+ if (offset_table_offset < BPLIST_MAGIC_SIZE + BPLIST_VERSION_SIZE || offset_table_offset >= max_valid_offset) {
PLIST_BIN_ERR("offset table offset points outside of valid range\n");
return PLIST_ERR_PARSE;
}
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