Re: [syzbot] [ocfs2?] general protection fault in ocfs2_prepare_dir_for_insert

[Edward Adam Davis]

i_size_read(dir) too big, make limit overflow, cause last_de uninit.

#syz test: upstream b0da640826ba

diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index d620d4c53c6f..c308dba6d213 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -3343,6 +3343,8 @@ static int ocfs2_find_dir_space_id(struct inode *dir, struct buffer_head *di_bh,
 	unsigned long offset = 0;
 	unsigned int rec_len, new_rec_len, free_space;
 
+	if (i_size_read(dir) > OCFS2_MAX_BLOCKSIZE)
+		return -EINVAL;
 	/*
 	 * This calculates how many free bytes we'd have in block zero, should
 	 * this function force expansion to an extent tree.