From: Eric Biggers <ebiggers@xxxxxxxxxx>
commit ccd30a476f8e864732de220bd50e6f372f5ebcab upstream.
Commit d7e7b9af104c ("fscrypt: stop using keyrings subsystem for
fscrypt_master_key") moved the keyring destruction from __put_super() to
generic_shutdown_super() so that the filesystem's block device(s) are
still available. Unfortunately, this causes a memory leak in the case
where a mount is attempted with the test_dummy_encryption mount option,
but the mount fails after the option has already been processed.
To fix this, attempt the keyring destruction in both places.
Reported-by: syzbot+104c2a89561289cec13e@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key")
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20221011213838.209879-1-ebiggers@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/crypto/keyring.c | 17 +++++++++++------
fs/super.c | 3 ++-
include/linux/fscrypt.h | 4 ++--
3 files changed, 15 insertions(+), 9 deletions(-)
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -202,14 +202,19 @@ static int allocate_filesystem_keyring(s
}
/*
- * This is called at unmount time to release all encryption keys that have been
- * added to the filesystem, along with the keyring that contains them.
+ * Release all encryption keys that have been added to the filesystem, along
+ * with the keyring that contains them.
*
- * Note that besides clearing and freeing memory, this might need to evict keys
- * from the keyslots of an inline crypto engine. Therefore, this must be called
- * while the filesystem's underlying block device(s) are still available.
+ * This is called at unmount time. The filesystem's underlying block device(s)
+ * are still available at this time; this is important because after user file
+ * accesses have been allowed, this function may need to evict keys from the
+ * keyslots of an inline crypto engine, which requires the block device(s).
+ *
+ * This is also called when the super_block is being freed. This is needed to
+ * avoid a memory leak if mounting fails after the "test_dummy_encryption"
+ * option was processed, as in that case the unmount-time call isn't made.
*/
-void fscrypt_sb_delete(struct super_block *sb)
+void fscrypt_destroy_keyring(struct super_block *sb)
{
struct fscrypt_keyring *keyring = sb->s_master_keys;
size_t i;
--- a/fs/super.c
+++ b/fs/super.c
@@ -293,6 +293,7 @@ static void __put_super(struct super_blo
WARN_ON(s->s_inode_lru.node);
WARN_ON(!list_empty(&s->s_mounts));
security_sb_free(s);
+ fscrypt_destroy_keyring(s);
put_user_ns(s->s_user_ns);
kfree(s->s_subtype);
call_rcu(&s->rcu, destroy_super_rcu);
@@ -453,7 +454,7 @@ void generic_shutdown_super(struct super
evict_inodes(sb);
/* only nonzero refcount inodes can have marks */
fsnotify_sb_delete(sb);
- fscrypt_sb_delete(sb);
+ fscrypt_destroy_keyring(sb);
if (sb->s_dio_done_wq) {
destroy_workqueue(sb->s_dio_done_wq);
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -193,7 +193,7 @@ fscrypt_free_dummy_policy(struct fscrypt
}
/* keyring.c */
-void fscrypt_sb_delete(struct super_block *sb);
+void fscrypt_destroy_keyring(struct super_block *sb);
int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *arg);
@@ -380,7 +380,7 @@ fscrypt_free_dummy_policy(struct fscrypt
}
/* keyring.c */
-static inline void fscrypt_sb_delete(struct super_block *sb)
+static inline void fscrypt_destroy_keyring(struct super_block *sb)
{
}
