make-docfile: don't corrupt heap for an invalid .elc file

2 files changed, 17 insertions, 3 deletions

diff --git a/lib-src/ChangeLog b/lib-src/ChangeLog
index bc76c253ab3..6428819daa3 100644
--- a/lib-src/ChangeLog
+++ b/lib-src/ChangeLog
@@ -1,3 +1,11 @@
+2011-01-30  Jim Meyering  <meyering@redhat.com>
+
+        make-docfile: don't corrupt heap for an invalid .elc file
+        "printf '#@1a' > in.elc; ./make-docfile in.elc" would store 0
+        one byte before just-malloc'd saved_string buffer.
+        * make-docfile.c (scan_lisp_file): Diagnose an invalid dynamic
+        doc string length.  Also fix an always-false while-loop test.
+
 2011-01-29  Eli Zaretskii  <eliz@gnu.org>
 
         * makefile.w32-in (LOCAL_FLAGS): Add -I../lib.
diff --git a/lib-src/make-docfile.c b/lib-src/make-docfile.c
index 0872f9728a2..8addbda0489 100644
--- a/lib-src/make-docfile.c
+++ b/lib-src/make-docfile.c
@@ -873,8 +873,8 @@ scan_lisp_file (const char *filename, const char *mode)
           c = getc (infile);
           if (c == '@')
             {
-              int length = 0;
-              int i;
+              size_t length = 0;
+              size_t i;
 
               /* Read the length.  */
               while ((c = getc (infile),
@@ -884,6 +884,12 @@ scan_lisp_file (const char *filename, const char *mode)
                   length += c - '0';
                 }
 
+              if (length <= 1)
+                fatal ("invalid dynamic doc string length", "");
+
+              if (c != ' ')
+                fatal ("space not found after dynamic doc string length", "");
+
               /* The next character is a space that is counted in the length
                  but not part of the doc string.
                  We already read it, so just ignore it.  */
@@ -899,7 +905,7 @@ scan_lisp_file (const char *filename, const char *mode)
                  but it is redundant in DOC.  So get rid of it here.  */
               saved_string[length - 1] = 0;
               /* Skip the line break.  */
-              while (c == '\n' && c == '\r')
+              while (c == '\n' || c == '\r')
                 c = getc (infile);
               /* Skip the following line.  */
               while (c != '\n' && c != '\r')