From patchwork Tue Oct 11 21:38:38 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 614323 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8043DC433FE for ; Tue, 11 Oct 2022 21:41:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229501AbiJKVll (ORCPT ); Tue, 11 Oct 2022 17:41:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50052 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229451AbiJKVlj (ORCPT ); Tue, 11 Oct 2022 17:41:39 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0349A02F7; Tue, 11 Oct 2022 14:41:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C81DD608C0; Tue, 11 Oct 2022 21:41:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 05E5CC433D6; Tue, 11 Oct 2022 21:41:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1665524495; bh=i0m1nXSGQ7El8zKzDjINCWdp5TGe82jc/TYesmzF5iE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BxVPDy7544JIgvkVqmCAsUmBwUC+QkgAdtyfDN26P27d3ZwGZr1KYoUXoDAoOWlEh 5Va9mHXs9PXPW9GxorQePLAkVQtT8vsgpFOGYgxb5Dp7n6MbdaKkzjpXpoTMgvgm0Z UcOfs+7AwSrHEEItI+UBKXlSa33oGVn6vyquazKRciv4T97UcOqliEEUxGtwuTpogb QFa+4+8ZXsXj8DAt49C8gVgPzfbhO7B6ejBjhDaKD+R6eANOyYode7LJps5xRoVmAR w1SNI7ll/J4AkmGcLGwT3rw6SSUrD6SoPwFGoXAzz9fPX4Qo/X6erxfCQ/qd/LCMSX KEncYvs4YMOHQ== From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, syzbot+104c2a89561289cec13e@syzkaller.appspotmail.com Subject: [PATCH] fscrypt: fix keyring memory leak on mount failure Date: Tue, 11 Oct 2022 14:38:38 -0700 Message-Id: <20221011213838.209879-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <0000000000009aad5e05eac85f36@google.com> References: <0000000000009aad5e05eac85f36@google.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org From: Eric Biggers 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 Reviewed-by: Christian Brauner (Microsoft) --- fs/crypto/keyring.c | 17 +++++++++++------ fs/super.c | 3 ++- include/linux/fscrypt.h | 4 ++-- 3 files changed, 15 insertions(+), 9 deletions(-) base-commit: 041bc24d867a2a577a06534d6d25e500b24a01ef diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index 1cca09aa43f8b..2a24b1f0ae688 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -205,14 +205,19 @@ 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 cad78b569c7ef..4f5f8a6512132 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -307,7 +307,7 @@ 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); @@ -521,7 +521,7 @@ 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) { }