[PATCH 27/30] ocfs2: check fast symlink dinodes in online filecheck

[Joseph Qi <joseph.qi@linux.alibaba.com>]

Wire the fast symlink guard and its two sub-checks into the filecheck
validator: an i_size beyond the space available for id2.i_symlink, and a
target that is not NUL-terminated at i_size.

ocfs2_dinode_has_unterminated_fast_symlink() bounds its own strnlen()
against ocfs2_fast_symlink_chars(), so this caller does not have to rely
on the size check having run first to stay inside the inode block.

Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
---
 fs/ocfs2/inode.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 06b190b00590..81f1f511d448 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -2130,6 +2130,30 @@ static int ocfs2_filecheck_validate_inode_block(struct super_block *sb,
 		}
 	}
 
+	if (ocfs2_dinode_is_fast_symlink(di)) {
+		int max_inline = ocfs2_fast_symlink_chars(sb);
+		u64 i_size = le64_to_cpu(di->i_size);
+
+		if (ocfs2_dinode_has_oversized_fast_symlink(sb, di)) {
+			mlog(ML_ERROR,
+			     "Filecheck: invalid dinode #%llu: fast symlink i_size %llu exceeds max %d\n",
+			     (unsigned long long)bh->b_blocknr,
+			     (unsigned long long)i_size,
+			     max_inline - 1);
+			rc = -OCFS2_FILECHECK_ERR_INVALIDINO;
+			goto bail;
+		}
+
+		if (ocfs2_dinode_has_unterminated_fast_symlink(sb, di)) {
+			mlog(ML_ERROR,
+			     "Filecheck: invalid dinode #%llu: fast symlink is not NUL-terminated at i_size %llu\n",
+			     (unsigned long long)bh->b_blocknr,
+			     (unsigned long long)i_size);
+			rc = -OCFS2_FILECHECK_ERR_INVALIDINO;
+			goto bail;
+		}
+	}
+
 bail:
 	return rc;
 }
-- 
2.39.3