ico: Always set errors

When the ico header turn out to be bad, always set an
error when we fail. Otherwise, applications will get
confused.

This commit also adds an example image with a bad ico header.

https://bugzilla.gnome.org/show_bug.cgi?id=768484

2 files changed, 12 insertions, 2 deletions

diff --git a/gdk-pixbuf/io-ico.c b/gdk-pixbuf/io-ico.c
index 86714affe..82d3e4e7a 100644
--- a/gdk-pixbuf/io-ico.c
+++ b/gdk-pixbuf/io-ico.c
@@ -258,8 +258,13 @@ static void DecodeHeader(guchar *Data, gint Bytes,
 		State->HeaderBuf = tmp;
  		State->BytesInHeaderBuf = State->HeaderSize;
  	}
- 	if (Bytes < State->HeaderSize)
+ 	if (Bytes < State->HeaderSize) {
+		g_set_error_literal (error,
+                                     GDK_PIXBUF_ERROR,
+                                     GDK_PIXBUF_ERROR_CORRUPT_IMAGE,
+                                     _("Not enough bytes for header"));
  		return;
+	}
 
 	/* Now iterate through the ICONDIRENTRY structures, and sort them by
 	 * which one we think is "best" (essentially the largest) */
@@ -399,8 +404,13 @@ static void DecodeHeader(guchar *Data, gint Bytes,
 		State->HeaderBuf = tmp;
  		State->BytesInHeaderBuf = State->HeaderSize;
  	}
- 	if (Bytes < State->HeaderSize)
+ 	if (Bytes < State->HeaderSize) {
+		g_set_error_literal (error,
+                                     GDK_PIXBUF_ERROR,
+                                     GDK_PIXBUF_ERROR_CORRUPT_IMAGE,
+                                     _("Not enough bytes for header"));
  		return;
+	}
 
 	/* Negative heights mean top-down pixel-order */
 	if (State->Header.height < 0) {
diff --git a/tests/test-images/randomly-modified/bad-header.ico b/tests/test-images/randomly-modified/bad-header.ico
new file mode 100644
index 000000000..ddf451575
--- /dev/null
+++ b/tests/test-images/randomly-modified/bad-header.ico