From: Ben Pfaff <blp@cs.stanford.edu>
Date: Tue, 1 Jan 2019 08:36:05 -0800
Subject: [PATCH] pspp-dump-sav: Issue error message for too-large extension
 records.

CVE-2018-20230.

diff --git a/utilities/pspp-dump-sav.c b/utilities/pspp-dump-sav.c
index aeb64866..b0001ac6 100644
--- a/utilities/pspp-dump-sav.c
+++ b/utilities/pspp-dump-sav.c
@@ -37,6 +37,7 @@
 #include "gl/progname.h"
 #include "gl/version-etc.h"
 #include "gl/xalloc.h"
+#include "gl/xsize.h"
 
 #define ID_MAX_LEN 64
 
@@ -99,7 +100,7 @@ static void read_simple_compressed_data (struct sfm_reader *, int max_cases);
 static void read_zlib_compressed_data (struct sfm_reader *);
 
 static struct text_record *open_text_record (
-  struct sfm_reader *, size_t size);
+  struct sfm_reader *, size_t size, size_t count);
 static void close_text_record (struct text_record *);
 static bool read_variable_to_value_pair (struct text_record *,
                                          char **key, char **value);
@@ -735,7 +736,7 @@ read_extra_product_info (struct sfm_reader *r,
   const char *s;
 
   printf ("%08llx: extra product info\n", (long long int) ftello (r->file));
-  text = open_text_record (r, size * count);
+  text = open_text_record (r, size, count);
   s = text_get_all (text);
   print_string (s, strlen (s));
   close_text_record (text);
@@ -749,7 +750,7 @@ read_mrsets (struct sfm_reader *r, size_t size, size_t count)
 
   printf ("%08llx: multiple response sets\n",
           (long long int) ftello (r->file));
-  text = open_text_record (r, size * count);
+  text = open_text_record (r, size, count);
   for (;;)
     {
       const char *name;
@@ -909,7 +910,7 @@ read_long_var_name_map (struct sfm_reader *r, size_t size, size_t count)
 
   printf ("%08llx: long variable names (short => long)\n",
           (long long int) ftello (r->file));
-  text = open_text_record (r, size * count);
+  text = open_text_record (r, size, count);
   while (read_variable_to_value_pair (text, &var, &long_name))
     printf ("\t%s => %s\n", var, long_name);
   close_text_record (text);
@@ -926,7 +927,7 @@ read_long_string_map (struct sfm_reader *r, size_t size, size_t count)
 
   printf ("%08llx: very long strings (variable => length)\n",
           (long long int) ftello (r->file));
-  text = open_text_record (r, size * count);
+  text = open_text_record (r, size, count);
   while (read_variable_to_value_pair (text, &var, &length_s))
     printf ("\t%s => %d\n", var, atoi (length_s));
   close_text_record (text);
@@ -1004,7 +1005,7 @@ read_datafile_attributes (struct sfm_reader *r, size_t size, size_t count)
   struct text_record *text;
 
   printf ("%08llx: datafile attributes\n", (long long int) ftello (r->file));
-  text = open_text_record (r, size * count);
+  text = open_text_record (r, size, count);
   read_attributes (r, text, "datafile");
   close_text_record (text);
 }
@@ -1196,7 +1197,7 @@ read_variable_attributes (struct sfm_reader *r, size_t size, size_t count)
   struct text_record *text;
 
   printf ("%08llx: variable attributes\n", (long long int) ftello (r->file));
-  text = open_text_record (r, size * count);
+  text = open_text_record (r, size, count);
   for (;;)
     {
       const char *variable = text_tokenize (text, ':');
@@ -1389,18 +1390,23 @@ struct text_record
     size_t pos;                 /* Current position in buffer. */
   };
 
-/* Reads SIZE bytes into a text record for R,
+/* Reads SIZE * COUNT bytes into a text record for R,
    and returns the new text record. */
 static struct text_record *
-open_text_record (struct sfm_reader *r, size_t size)
+open_text_record (struct sfm_reader *r, size_t size, size_t count)
 {
   struct text_record *text = xmalloc (sizeof *text);
-  char *buffer = xmalloc (size + 1);
-  read_bytes (r, buffer, size);
+
+  if (size_overflow_p (xsum (1, xtimes (size, count))))
+    sys_error (r, "Extension record too large.");
+
+  size_t n_bytes = size * count;
+  char *buffer = xmalloc (n_bytes + 1);
+  read_bytes (r, buffer, n_bytes);
   buffer[size] = '\0';
   text->reader = r;
   text->buffer = buffer;
-  text->size = size;
+  text->size = n_bytes;
   text->pos = 0;
   return text;
 }