shithub: puzzles

Download patch

ref: c3a5a7842eb6c41fb75a8a110a3f2cbc1c8fc5d9
parent: ffe2fa169f9fdc411d00e1c75cf3cdc5f3099727
author: Ben Harris <bjh21@bjh21.me.uk>
date: Sun Feb 12 18:04:12 EST 2023

Validate that save file values are ASCII (mostly)

Apart from "SEED" records, all values in save files generated by Puzzles
should be printable ASCII.  This is enforced by assertion in the saving
code.  However, if a save file with non-ASCII move strings (for
instance) manages to get loaded then these non-ASCII values can cause an
assertion failure on saving.  Instead, the loading code now checks
values for ASCIIness.

This will not only avoid problems when re-saving files, but will also
defend the various internal parsers from at least some evil strings.  It
shouldn't invalidate any save files actually generated by Puzzles, but
it will sadly invalidate some of my fuzzing corpus.

--- a/midend.c
+++ b/midend.c
@@ -2329,6 +2329,13 @@
             goto cleanup;
         }
         val[len] = '\0';
+        /* Validate that all values (apart from SEED) are printable ASCII. */
+        if (strcmp(key, "SEED"))
+            for (i = 0; val[i]; i++)
+                if (val[i] < 32 || val[i] >= 127) {
+                    ret = "Forbidden characters in saved game file";
+                    goto cleanup;
+                }
 
         if (!started) {
             if (strcmp(key, "SAVEFILE") || strcmp(val, SERIALISE_MAGIC)) {