* lread.c: Integer overflow issues.

(saved_doc_string_size, saved_doc_string_length)
(prev_saved_doc_string_size, prev_saved_doc_string_length):
Now ptrdiff_t, not int.
(read1): Don't assume doc string length fits in int.  Check for
out-of-range doc string lengths.
(read_list): Don't assume file position fits in int.

2 files changed, 21 insertions, 10 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 78fca60ca28..f0a48ed75ab 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,13 @@
 2011-06-22  Paul Eggert  <eggert@cs.ucla.edu>
 
+        * lread.c: Integer overflow issues.
+        (saved_doc_string_size, saved_doc_string_length)
+        (prev_saved_doc_string_size, prev_saved_doc_string_length):
+        Now ptrdiff_t, not int.
+        (read1): Don't assume doc string length fits in int.  Check for
+        out-of-range doc string lengths.
+        (read_list): Don't assume file position fits in int.
+
         Fixes for GLYPH_DEBUG found by GCC 4.6.0 static checking.
         The following patches are for when GLYPH_DEBUG && !XASSERT.
         * dispextern.h (trace_redisplay_p, dump_glyph_string):
diff --git a/src/lread.c b/src/lread.c
index e75d61ae985..42ddbfd188d 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -120,9 +120,9 @@ static EMACS_INT readchar_count;
 /* This contains the last string skipped with #@.  */
 static char *saved_doc_string;
 /* Length of buffer allocated in saved_doc_string.  */
-static int saved_doc_string_size;
+static ptrdiff_t saved_doc_string_size;
 /* Length of actual data in saved_doc_string.  */
-static int saved_doc_string_length;
+static ptrdiff_t saved_doc_string_length;
 /* This is the file position that string came from.  */
 static file_offset saved_doc_string_position;
 
@@ -131,9 +131,9 @@ static file_offset saved_doc_string_position;
    is put in saved_doc_string.  */
 static char *prev_saved_doc_string;
 /* Length of buffer allocated in prev_saved_doc_string.  */
-static int prev_saved_doc_string_size;
+static ptrdiff_t prev_saved_doc_string_size;
 /* Length of actual data in prev_saved_doc_string.  */
-static int prev_saved_doc_string_length;
+static ptrdiff_t prev_saved_doc_string_length;
 /* This is the file position that string came from.  */
 static file_offset prev_saved_doc_string_position;
 
@@ -2569,13 +2569,16 @@ read1 (register Lisp_Object readcharfun, int *pch, int first_in_list)
          and function definitions.  */
       if (c == '@')
         {
-          int i, nskip = 0;
+          enum { extra = 100 };
+          ptrdiff_t i, nskip = 0;
 
           load_each_byte = 1;
           /* Read a decimal integer.  */
           while ((c = READCHAR) >= 0
                  && c >= '0' && c <= '9')
             {
+              if ((STRING_BYTES_BOUND - extra) / 10 <= nskip)
+                string_overflow ();
               nskip *= 10;
               nskip += c - '0';
             }
@@ -2594,9 +2597,9 @@ read1 (register Lisp_Object readcharfun, int *pch, int first_in_list)
                  with prev_saved_doc_string, so we save two strings.  */
               {
                 char *temp = saved_doc_string;
-                int temp_size = saved_doc_string_size;
+                ptrdiff_t temp_size = saved_doc_string_size;
                 file_offset temp_pos = saved_doc_string_position;
-                int temp_len = saved_doc_string_length;
+                ptrdiff_t temp_len = saved_doc_string_length;
 
                 saved_doc_string = prev_saved_doc_string;
                 saved_doc_string_size = prev_saved_doc_string_size;
@@ -2611,12 +2614,12 @@ read1 (register Lisp_Object readcharfun, int *pch, int first_in_list)
 
               if (saved_doc_string_size == 0)
                 {
-                  saved_doc_string_size = nskip + 100;
+                  saved_doc_string_size = nskip + extra;
                   saved_doc_string = (char *) xmalloc (saved_doc_string_size);
                 }
               if (nskip > saved_doc_string_size)
                 {
-                  saved_doc_string_size = nskip + 100;
+                  saved_doc_string_size = nskip + extra;
                   saved_doc_string = (char *) xrealloc (saved_doc_string,
                                                         saved_doc_string_size);
                 }
@@ -3528,7 +3531,7 @@ read_list (int flag, register Lisp_Object readcharfun)
                          doc string, caller must make it
                          multibyte.  */
 
-                      int pos = XINT (XCDR (val));
+                      EMACS_INT pos = XINT (XCDR (val));
                       /* Position is negative for user variables.  */
                       if (pos < 0) pos = -pos;
                       if (pos >= saved_doc_string_position