From: Eric Biggers ebiggers@google.com
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@syzkaller.appspotmail.com Fixes: d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key") Signed-off-by: Eric Biggers ebiggers@google.com Reviewed-by: Christian Brauner (Microsoft) brauner@kernel.org Link: https://lore.kernel.org/r/20221011213838.209879-1-ebiggers@kernel.org --- fs/crypto/keyring.c | 17 +++++++++++------ fs/super.c | 3 ++- include/linux/fscrypt.h | 4 ++-- 3 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index 9b98d6a576e6a..f10ace12c05f8 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -202,14 +202,19 @@ static int allocate_filesystem_keyring(struct super_block *sb) }
/* - * 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; diff --git a/fs/super.c b/fs/super.c index 6a82660e1adba..8d39e4f11cfa3 100644 --- a/fs/super.c +++ b/fs/super.c @@ -291,6 +291,7 @@ static void __put_super(struct super_block *s) 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); @@ -479,7 +480,7 @@ void generic_shutdown_super(struct super_block *sb) evict_inodes(sb); /* only nonzero refcount inodes can have marks */ fsnotify_sb_delete(sb); - fscrypt_sb_delete(sb); + fscrypt_destroy_keyring(sb); security_sb_delete(sb);
if (sb->s_dio_done_wq) { diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index d86f43bd95502..d0e40a20ff810 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -312,7 +312,7 @@ fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy) }
/* 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_add_test_dummy_key(struct super_block *sb, const struct fscrypt_dummy_policy *dummy_policy); @@ -526,7 +526,7 @@ fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy) }
/* keyring.c */ -static inline void fscrypt_sb_delete(struct super_block *sb) +static inline void fscrypt_destroy_keyring(struct super_block *sb) { }