ubifs: Rectify space budget for ubifs_symlink() if symlink is encrypted

Fix bad space budget when symlink file is encrypted. Bad space budget
may let make_reservation() return with -ENOSPC, which could turn ubifs
to read-only mode in do_writepage() process.

Fetch a reproducer in [Link].

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216490
Fixes: ca7f85be8d6cf9 ("ubifs: Add support for encrypted symlinks")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 0f29cf2..aaff3f3 100644 (file)
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1151,7 +1151,6 @@ static int ubifs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
        int err, sz_change, len = strlen(symname);
        struct fscrypt_str disk_link;
        struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
-                                       .new_ino_d = ALIGN(len, 8),
                                        .dirtied_ino = 1 };
        struct fscrypt_name nm;
 
@@ -1167,6 +1166,7 @@ static int ubifs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
         * Budget request settings: new inode, new direntry and changing parent
         * directory inode.
         */
+       req.new_ino_d = ALIGN(disk_link.len - 1, 8);
        err = ubifs_budget_space(c, &req);
        if (err)
                return err;