Commit 4bcf6f82 authored by Eric Biggers's avatar Eric Biggers
Browse files

fscrypt: check for NULL keyring in fscrypt_put_master_key_activeref() 

It is a bug for fscrypt_put_master_key_activeref() to see a NULL
keyring.  But it used to be possible due to the bug, now fixed, where
fscrypt_destroy_keyring() was called before security_sb_delete().  To be
consistent with how fscrypt_destroy_keyring() uses WARN_ON for the same
issue, WARN and leak the fscrypt_master_key if the keyring is NULL
instead of dereferencing the NULL pointer.

This is a robustness improvement, not a fix.

Link: https://lore.kernel.org/r/20230313221231.272498-4-ebiggers@kernel.org


Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent 43e5f1d5

fs/crypto/keyring.c

+2 −0
Original line number Diff line number Diff line
@@ -92,6 +92,8 @@ void fscrypt_put_master_key_activeref(struct super_block *sb, 
	 * destroying any subkeys embedded in it.

	 */



	if (WARN_ON(!sb->s_master_keys))

		return;

	spin_lock(&sb->s_master_keys->lock);

	hlist_del_rcu(&mk->mk_node);

	spin_unlock(&sb->s_master_keys->lock);