CVE-2017-6439 (published 2017-03-15T14:59Z)

Heap-based buffer overflow in the parse_string_node function in bplist.c in libimobiledevice libplist 1.12 allows local users to cause a denial of service (out-of-bounds write) via a crafted plist file.

Severity: LOW
CVSS v2 base score: 1.9 (AV:L/AC:M/Au:N/C:N/I:N/A:P)
CVSS v3 base score: 5.0, MEDIUM (CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: CWE-787
cwe_name: Out-of-bounds Write
description: The product writes data past the end, or before the beginning, of the intended buffer.
extended_description: 
            
            
             
			 
         
         

Fix information:
repo_url: https://github.com/libimobiledevice/libplist
commit_details: repo_url: https://github.com/libimobiledevice/libplist
author: Nikias Bassen
author_date: 2017-02-10 13:42:46+01:00
msg: bplist: Fix data range check for string/data/dict/array nodes

Passing a size of 0xFFFFFFFFFFFFFFFF to parse_string_node() might result
in a memcpy with a size of -1, leading to undefined behavior.
This commit makes sure that the actual node data (which depends on the size)
is in the range start_of_object..start_of_object+size.

Credit to OSS-Fuzz
repository: repo_url: https://github.com/libimobiledevice/libplist
repo_name: libimobiledevice/libplist
description: A library to handle Apple Property List format in binary or XML
repo_language: C
owner: libimobiledevice
file_changes: filename: bplist.c
change_type: ModificationType.MODIFY
diff: @@ -654,14 +654,14 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
         return parse_date_node(object, size);
 
     case BPLIST_DATA:
-        if (*object + size > bplist->offset_table) {
+        if (*object + size < *object || *object + size > bplist->offset_table) {
             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 (*object + size > bplist->offset_table) {
+        if (*object + size < *object || *object + size > bplist->offset_table) {
             PLIST_BIN_ERR("%s: BPLIST_STRING data bytes point outside of valid range\n", __func__);
             return NULL;
         }
@@ -672,7 +672,7 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
             PLIST_BIN_ERR("%s: Integer overflow when calculating BPLIST_UNICODE data size.\n", __func__);
             return NULL;
         }
-        if (*object + size*2 > bplist->offset_table) {
+        if (*object + size*2 < *object || *object + size*2 > bplist->offset_table) {
             PLIST_BIN_ERR("%s: BPLIST_UNICODE data bytes point outside of valid range\n", __func__);
             return NULL;
         }
@@ -680,7 +680,7 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
 
     case BPLIST_SET:
     case BPLIST_ARRAY:
-        if (*object + size > bplist->offset_table) {
+        if (*object + size < *object || *object + size > bplist->offset_table) {
             PLIST_BIN_ERR("%s: BPLIST_ARRAY data bytes point outside of valid range\n", __func__);
             return NULL;
         }
@@ -694,8 +694,8 @@ static plist_t parse_bin_node(struct bplist_data *bplist, const char** object)
         return parse_uid_node(object, size);
 
     case BPLIST_DICT:
-        if (*object + size > bplist->offset_table) {
-            PLIST_BIN_ERR("%s: BPLIST_REAL data bytes point outside of valid range\n", __func__);
+        if (*object + size < *object || *object + size > bplist->offset_table) {
+            PLIST_BIN_ERR("%s: BPLIST_DICT data bytes point outside of valid range\n", __func__);
             return NULL;
         }
         return parse_dict_node(bplist, object, size);

programming_language: C