[PATCH 2/3] ubifs: xattr: preserve the encryption flag when creation fails

[shao.mingyin]

create_xattr() clears UBIFS_CRYPT_FL in its error path regardless of
whether this call set the flag.  The flag is also set for every inode
that already carries an encryption context, so a failed setxattr() on
such an inode clears it from the in-memory inode.  The next inode write
then packs ui->flags without UBIFS_CRYPT_FL, and after the next mount
the inode is no longer treated as encrypted although its names and data
still are.  ubifs_jnl_update() can fail before anything is written, for
example when its journal buffer cannot be allocated.

Remember whether this call actually set the flag and only clear it in
that case.

Fixes: d475a507457b ("ubifs: Add skeleton for fscrypto")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Shao Mingyin <shao.mingyin@xxxxxxxxxx>
---
diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
index 3b0e8a270f59..7f82ddb9e3f2 100644
--- a/fs/ubifs/xattr.c
+++ b/fs/ubifs/xattr.c
@@ -69,6 +69,7 @@ static int create_xattr(struct ubifs_info *c, struct inode *host,
 			const struct fscrypt_name *nm, const void *value, int size)
 {
 	int err, names_len;
+	bool set_crypt = false;
 	struct inode *inode;
 	struct ubifs_inode *ui, *host_ui = ubifs_inode(host);
 	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
@@ -133,8 +134,10 @@ static int create_xattr(struct ubifs_info *c, struct inode *host,
 	 * To avoid multiple updates of the same inode in the same operation,
 	 * let's do it here.
 	 */
-	if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
+	if (strcmp(fname_name(nm), UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0) {
+		set_crypt = !(host_ui->flags & UBIFS_CRYPT_FL);
 		host_ui->flags |= UBIFS_CRYPT_FL;
+	}
 
 	err = ubifs_jnl_update(c, host, nm, inode, 0, 1, 0);
 	if (err)
@@ -152,7 +155,8 @@ static int create_xattr(struct ubifs_info *c, struct inode *host,
 	host_ui->xattr_size -= CALC_DENT_SIZE(fname_len(nm));
 	host_ui->xattr_size -= CALC_XATTR_BYTES(size);
 	host_ui->xattr_names -= fname_len(nm);
-	host_ui->flags &= ~UBIFS_CRYPT_FL;
+	if (set_crypt)
+		host_ui->flags &= ~UBIFS_CRYPT_FL;
 	mutex_unlock(&host_ui->ui_mutex);
 out_free:
 	make_bad_inode(inode);