[Ocfs2-devel] [PATCH] Revert "fs: ocfs2: fix possible null-pointer dereferences in ocfs2_xa_prepare_entry()"

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

This reverts commit 56e94ea132bb5c2c1d0b60a6aeb34dcb7d71a53d.

commit 56e94ea132bb "fs: ocfs2: fix possible null-pointer dereferences
in ocfs2_xa_prepare_entry()" introduces a regression that fail to create
directory with mount option user_xattr and acl.
Actually the reported NULL pointer dereference case can be correctly
handled by loc->xl_ops->xlo_add_entry(), so revert it.

Reported-by: Thomas Voegtle <tv@lio96.de>
Cc: Jia-Ju Bai <baijiaju1990@gmail.com>
Cc: stable at vger.kernel.org
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
---
 fs/ocfs2/xattr.c | 56 +++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 33 insertions(+), 23 deletions(-)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index d850797..90c830e3 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -1490,6 +1490,18 @@ static int ocfs2_xa_check_space(struct ocfs2_xa_loc *loc,
 	return loc->xl_ops->xlo_check_space(loc, xi);
 }
 
+static void ocfs2_xa_add_entry(struct ocfs2_xa_loc *loc, u32 name_hash)
+{
+	loc->xl_ops->xlo_add_entry(loc, name_hash);
+	loc->xl_entry->xe_name_hash = cpu_to_le32(name_hash);
+	/*
+	 * We can't leave the new entry's xe_name_offset at zero or
+	 * add_namevalue() will go nuts.  We set it to the size of our
+	 * storage so that it can never be less than any other entry.
+	 */
+	loc->xl_entry->xe_name_offset = cpu_to_le16(loc->xl_size);
+}
+
 static void ocfs2_xa_add_namevalue(struct ocfs2_xa_loc *loc,
 				   struct ocfs2_xattr_info *xi)
 {
@@ -2121,31 +2133,29 @@ static int ocfs2_xa_prepare_entry(struct ocfs2_xa_loc *loc,
 	if (rc)
 		goto out;
 
-	if (!loc->xl_entry) {
-		rc = -EINVAL;
-		goto out;
-	}
-
-	if (ocfs2_xa_can_reuse_entry(loc, xi)) {
-		orig_value_size = loc->xl_entry->xe_value_size;
-		rc = ocfs2_xa_reuse_entry(loc, xi, ctxt);
-		if (rc)
-			goto out;
-		goto alloc_value;
-	}
+	if (loc->xl_entry) {
+		if (ocfs2_xa_can_reuse_entry(loc, xi)) {
+			orig_value_size = loc->xl_entry->xe_value_size;
+			rc = ocfs2_xa_reuse_entry(loc, xi, ctxt);
+			if (rc)
+				goto out;
+			goto alloc_value;
+		}
 
-	if (!ocfs2_xattr_is_local(loc->xl_entry)) {
-		orig_clusters = ocfs2_xa_value_clusters(loc);
-		rc = ocfs2_xa_value_truncate(loc, 0, ctxt);
-		if (rc) {
-			mlog_errno(rc);
-			ocfs2_xa_cleanup_value_truncate(loc,
-							"overwriting",
-							orig_clusters);
-			goto out;
+		if (!ocfs2_xattr_is_local(loc->xl_entry)) {
+			orig_clusters = ocfs2_xa_value_clusters(loc);
+			rc = ocfs2_xa_value_truncate(loc, 0, ctxt);
+			if (rc) {
+				mlog_errno(rc);
+				ocfs2_xa_cleanup_value_truncate(loc,
+								"overwriting",
+								orig_clusters);
+				goto out;
+			}
 		}
-	}
-	ocfs2_xa_wipe_namevalue(loc);
+		ocfs2_xa_wipe_namevalue(loc);
+	} else
+		ocfs2_xa_add_entry(loc, name_hash);
 
 	/*
 	 * If we get here, we have a blank entry.  Fill it.  We grow our
-- 
1.8.3.1