Fix tree.c->tree_get_entry_at() buffer overflow

I observed a crash on buflib>move_block
after dumping ram I noticed that the buffer for filetypes was being corrupted

tree_get_entry_at returns a entry from the buflib 'tree entry' buffer
filetree.c->ft_load writes data to this buffer before checking if it has
reached the last entry resulting in buffer overflow that overwrites the
next entry in the buffer ['filetypes']

Patch checks that the index passed to tree_get_entry_at() is in range
otherwise it returns NULL

Added checks + panic in other functions using tree_get_entry_at()
Fixed tree_lock_cache() calls in playlist and filetree

Change-Id: Ibf9e65652b4e00445e8e509629aebbcddffcfd4d

1 files changed, 2 insertions, 0 deletions

diff --git a/apps/tree.h b/apps/tree.h
index 77dc5da1b4..c70ae8dac1 100644
--- a/apps/tree.h
+++ b/apps/tree.h
@@ -105,7 +105,9 @@ struct tree_context {
 /*
  * Call one of the two below after yields since the entrys may move inbetween */
 struct entry* tree_get_entries(struct tree_context *t);
+/* returns NULL on invalid index */
 struct entry* tree_get_entry_at(struct tree_context *t, int index);
+
 void tree_mem_init(void) INIT_ATTR;
 void tree_gui_init(void) INIT_ATTR;
 char* get_current_file(char* buffer, size_t buffer_len);