File parser-Don-t-set-more-maps-when-we-don-t-have-any.patch of Package libxkbcommon.31860

From a8ea7a1d3daa7bdcb877615ae0a252c189153bd2 Mon Sep 17 00:00:00 2001
From: Daniel Stone <daniels@collabora.com>
Date: Mon, 26 Jun 2017 16:45:16 +0100
Subject: [PATCH] parser: Don't set more maps when we don't have any
Git-commit: a8ea7a1d3daa7bdcb877615ae0a252c189153bd2
Patch-mainline: xkbcommon-0.8.2
References: CVE-2018-15864

If the scanner indicates that we might have something which looks like a
map, but the parser in fact fails to create that map, we will try to
access the map regardless. Stop doing that.

Testcase: 'xkb_keymap {' -> '#kb_keymap'

Signed-off-by: Daniel Stone <daniels@collabora.com>

---
 src/xkbcomp/parser.y | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/xkbcomp/parser.y b/src/xkbcomp/parser.y
index b555bc2..296ce19 100644
--- a/src/xkbcomp/parser.y
+++ b/src/xkbcomp/parser.y
@@ -239,9 +239,9 @@ resolve_keysym(const char *name, xkb_keysym_t *sym_rtrn)
  */
 
 XkbFile         :       XkbCompositeMap
-                        { $$ = param->rtrn = $1; param->more_maps = true; }
+                        { $$ = param->rtrn = $1; param->more_maps = !!param->rtrn; }
                 |       XkbMapConfig
-                        { $$ = param->rtrn = $1; param->more_maps = true; YYACCEPT; }
+                        { $$ = param->rtrn = $1; param->more_maps = !!param->rtrn; YYACCEPT; }
                 |       END_OF_FILE
                         { $$ = param->rtrn = NULL; param->more_maps = false; }
                 ;
@@ -772,6 +772,7 @@ parse(struct xkb_context *ctx, struct scanner *scanner, const char *map)
         .scanner = scanner,
         .ctx = ctx,
         .rtrn = NULL,
+        .more_maps = false,
     };
 
     /*
-- 
2.35.3