[ 072/100] efivarfs: return accurate error code in efivarfs_fill_super()

[Greg Kroah-Hartman]

3.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Matt Fleming <matt.fleming@xxxxxxxxx>

commit feff5dc4f98330d8152b521acc2e18c16712e6c8 upstream.

Joseph was hitting a failure case when mounting efivarfs which
resulted in an incorrect error message,

  $ sudo mount -v /sys/firmware/efi/efivars mount: Cannot allocate memory

triggered when efivarfs_valid_name() returned -EINVAL.

Make sure we pass accurate return values up the stack if
efivarfs_fill_super() fails to build inodes for EFI variables.

Reported-by: Joseph Yasi <joe.yasi@xxxxxxxxx>
Reported-by: Lingzhu Xiang <lxiang@xxxxxxxxxx>
Cc: Josh Boyer <jwboyer@xxxxxxxxxx>
Cc: Jeremy Kerr <jk@xxxxxxxxxx>
Cc: Matthew Garrett <mjg59@xxxxxxxxxxxxx>
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/firmware/efivars.c |   20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -1110,15 +1110,22 @@ static struct dentry_operations efivarfs
 
 static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
 {
+	struct dentry *d;
 	struct qstr q;
+	int err;
 
 	q.name = name;
 	q.len = strlen(name);
 
-	if (efivarfs_d_hash(NULL, NULL, &q))
-		return NULL;
+	err = efivarfs_d_hash(NULL, NULL, &q);
+	if (err)
+		return ERR_PTR(err);
+
+	d = d_alloc(parent, &q);
+	if (d)
+		return d;
 
-	return d_alloc(parent, &q);
+	return ERR_PTR(-ENOMEM);
 }
 
 static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
@@ -1128,6 +1135,7 @@ static int efivarfs_fill_super(struct su
 	struct efivar_entry *entry, *n;
 	struct efivars *efivars = &__efivars;
 	char *name;
+	int err = -ENOMEM;
 
 	efivarfs_sb = sb;
 
@@ -1178,8 +1186,10 @@ static int efivarfs_fill_super(struct su
 			goto fail_name;
 
 		dentry = efivarfs_alloc_dentry(root, name);
-		if (!dentry)
+		if (IS_ERR(dentry)) {
+			err = PTR_ERR(dentry);
 			goto fail_inode;
+		}
 
 		/* copied by the above to local storage in the dentry. */
 		kfree(name);
@@ -1206,7 +1216,7 @@ fail_inode:
 fail_name:
 	kfree(name);
 fail:
-	return -ENOMEM;
+	return err;
 }
 
 static struct dentry *efivarfs_mount(struct file_system_type *fs_type,


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