Guard font functions against invalid font ids. These arguably should never be passed, but this prevents freezes. Fixes FS#12400

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31075 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 4 insertions, 2 deletions

diff --git a/firmware/font.c b/firmware/font.c
index d8f8c59e0d..2b86d338db 100644
--- a/firmware/font.c
+++ b/firmware/font.c
@@ -135,7 +135,7 @@ static void lock_font_handle(int handle, bool lock)
 
 void font_lock(int font_id, bool lock)
 {
-    if( font_id == FONT_SYSFIXED )
+    if( font_id < 0 || font_id >= MAXFONTS )
         return;
     if( buflib_allocations[font_id] >= 0 )
         lock_font_handle(buflib_allocations[font_id], lock);
@@ -340,6 +340,8 @@ static int find_font_index(const char* path)
 
 const char* font_filename(int font_id)
 {
+    if ( font_id < 0 || font_id >= MAXFONTS )
+        return NULL;
     int handle = buflib_allocations[font_id];
     if (handle > 0)
         return core_get_name(handle);
@@ -582,7 +584,7 @@ int font_load(const char *path)
 
 void font_unload(int font_id)
 {
-    if ( font_id == FONT_SYSFIXED )
+    if ( font_id < 0 || font_id >= MAXFONTS )
         return;
     int handle = buflib_allocations[font_id];
     if ( handle < 0 )