Fix CVE-2017-14687:

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-14687

Patch copied from upstream source repository:

https://git.ghostscript.com/?p=mupdf.git;h=2b16dbd8f73269cb15ca61ece75cf8d2d196ed28

From 2b16dbd8f73269cb15ca61ece75cf8d2d196ed28 Mon Sep 17 00:00:00 2001
From: Tor Andersson <tor.andersson@artifex.com>
Date: Tue, 19 Sep 2017 17:17:12 +0200
Subject: [PATCH] Fix 698558: Handle non-tags in tag name comparisons.

Use fz_xml_is_tag instead of fz_xml_tag && !strcmp idiom.
---
 source/html/css-apply.c   | 2 +-
 source/svg/svg-run.c      | 2 +-
 source/xps/xps-common.c   | 6 +++---
 source/xps/xps-glyphs.c   | 2 +-
 source/xps/xps-path.c     | 4 ++--
 source/xps/xps-resource.c | 2 +-
 6 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/source/html/css-apply.c b/source/html/css-apply.c
index de55490..6a91df0 100644
--- a/source/html/css-apply.c
+++ b/source/html/css-apply.c
@@ -328,7 +328,7 @@ match_selector(fz_css_selector *sel, fz_xml *node)
 
 	if (sel->name)
 	{
-		if (strcmp(sel->name, fz_xml_tag(node)))
+		if (!fz_xml_is_tag(node, sel->name))
 			return 0;
 	}
 
diff --git a/source/svg/svg-run.c b/source/svg/svg-run.c
index f974c67..5302c64 100644
--- a/source/svg/svg-run.c
+++ b/source/svg/svg-run.c
@@ -1044,7 +1044,7 @@ svg_run_use(fz_context *ctx, fz_device *dev, svg_document *doc, fz_xml *root, co
 		fz_xml *linked = fz_tree_lookup(ctx, doc->idmap, xlink_href_att + 1);
 		if (linked)
 		{
-			if (!strcmp(fz_xml_tag(linked), "symbol"))
+			if (fz_xml_is_tag(linked, "symbol"))
 				svg_run_use_symbol(ctx, dev, doc, root, linked, &local_state);
 			else
 				svg_run_element(ctx, dev, doc, linked, &local_state);
diff --git a/source/xps/xps-common.c b/source/xps/xps-common.c
index cc7fed9..f2f9b93 100644
--- a/source/xps/xps-common.c
+++ b/source/xps/xps-common.c
@@ -47,7 +47,7 @@ xps_parse_brush(fz_context *ctx, xps_document *doc, const fz_matrix *ctm, const
 	else if (fz_xml_is_tag(node, "RadialGradientBrush"))
 		xps_parse_radial_gradient_brush(ctx, doc, ctm, area, base_uri, dict, node);
 	else
-		fz_warn(ctx, "unknown brush tag: %s", fz_xml_tag(node));
+		fz_warn(ctx, "unknown brush tag");
 }
 
 void
@@ -85,7 +85,7 @@ xps_begin_opacity(fz_context *ctx, xps_document *doc, const fz_matrix *ctm, cons
 	if (opacity_att)
 		opacity = fz_atof(opacity_att);
 
-	if (opacity_mask_tag && !strcmp(fz_xml_tag(opacity_mask_tag), "SolidColorBrush"))
+	if (fz_xml_is_tag(opacity_mask_tag, "SolidColorBrush"))
 	{
 		char *scb_opacity_att = fz_xml_att(opacity_mask_tag, "Opacity");
 		char *scb_color_att = fz_xml_att(opacity_mask_tag, "Color");
@@ -129,7 +129,7 @@ xps_end_opacity(fz_context *ctx, xps_document *doc, char *base_uri, xps_resource
 
 	if (opacity_mask_tag)
 	{
-		if (strcmp(fz_xml_tag(opacity_mask_tag), "SolidColorBrush"))
+		if (!fz_xml_is_tag(opacity_mask_tag, "SolidColorBrush"))
 			fz_pop_clip(ctx, dev);
 	}
 }
diff --git a/source/xps/xps-glyphs.c b/source/xps/xps-glyphs.c
index 29dc5b3..5b26d78 100644
--- a/source/xps/xps-glyphs.c
+++ b/source/xps/xps-glyphs.c
@@ -592,7 +592,7 @@ xps_parse_glyphs(fz_context *ctx, xps_document *doc, const fz_matrix *ctm,
 
 	/* If it's a solid color brush fill/stroke do a simple fill */
 
-	if (fill_tag && !strcmp(fz_xml_tag(fill_tag), "SolidColorBrush"))
+	if (fz_xml_is_tag(fill_tag, "SolidColorBrush"))
 	{
 		fill_opacity_att = fz_xml_att(fill_tag, "Opacity");
 		fill_att = fz_xml_att(fill_tag, "Color");
diff --git a/source/xps/xps-path.c b/source/xps/xps-path.c
index 6faeb0c..021d202 100644
--- a/source/xps/xps-path.c
+++ b/source/xps/xps-path.c
@@ -879,14 +879,14 @@ xps_parse_path(fz_context *ctx, xps_document *doc, const fz_matrix *ctm, char *b
 	if (!data_att && !data_tag)
 		return;
 
-	if (fill_tag && !strcmp(fz_xml_tag(fill_tag), "SolidColorBrush"))
+	if (fz_xml_is_tag(fill_tag, "SolidColorBrush"))
 	{
 		fill_opacity_att = fz_xml_att(fill_tag, "Opacity");
 		fill_att = fz_xml_att(fill_tag, "Color");
 		fill_tag = NULL;
 	}
 
-	if (stroke_tag && !strcmp(fz_xml_tag(stroke_tag), "SolidColorBrush"))
+	if (fz_xml_is_tag(stroke_tag, "SolidColorBrush"))
 	{
 		stroke_opacity_att = fz_xml_att(stroke_tag, "Opacity");
 		stroke_att = fz_xml_att(stroke_tag, "Color");
diff --git a/source/xps/xps-resource.c b/source/xps/xps-resource.c
index c2292e6..8e81ab8 100644
--- a/source/xps/xps-resource.c
+++ b/source/xps/xps-resource.c
@@ -84,7 +84,7 @@ xps_parse_remote_resource_dictionary(fz_context *ctx, xps_document *doc, char *b
 	if (!xml)
 		return NULL;
 
-	if (strcmp(fz_xml_tag(xml), "ResourceDictionary"))
+	if (!fz_xml_is_tag(xml, "ResourceDictionary"))
 	{
 		fz_drop_xml(ctx, xml);
 		fz_throw(ctx, FZ_ERROR_GENERIC, "expected ResourceDictionary element");
-- 
2.9.1