From patchwork Wed Nov 2 05:33:12 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 13027726 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 A4DE8C4332F for ; Wed, 2 Nov 2022 05:34:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229493AbiKBFek (ORCPT ); Wed, 2 Nov 2022 01:34:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229487AbiKBFej (ORCPT ); Wed, 2 Nov 2022 01:34:39 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9D5E1154; Tue, 1 Nov 2022 22:34:38 -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 ams.source.kernel.org (Postfix) with ESMTPS id 9AD56B81F95; Wed, 2 Nov 2022 05:34:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AAF0C433C1; Wed, 2 Nov 2022 05:34:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667367276; bh=9BZw2j7gde3uJiIaOBImAvzx2MwQSpOziphx0uVUk3o=; h=From:To:Cc:Subject:Date:From; b=DQ38/mCYDwXIagRZfiVNCcZGXnw0cXNC0FWQxofIg4YIrCVk8+O52kl2uYNxpRpEu DvT3V0vlTdQJaXqC2O36GZddiVSyrpSn+ik+PUm10HUJbQV85qjYBoV1Q/UFLdQNOE HWBN65tr1G2Q/Of22/52mGhTFyrCgrfhM5JryFWz753JJJWifHpvoeMncbtlf1Ps9+ EN9nCdCt7Ql/h9ERlJSKQy3VI4niK455IC7xMjHWVoDA/0/DNLswHycSyrVgzApt88 waUllWAo6WY1UcB4XBjOgVTEMhlFJZZdCEVpGYOFP/pNFYQhUOtN+l8djo7uB5byNF RMeElC/0J5HRA== From: Eric Biggers To: linux-ext4@vger.kernel.org Cc: linux-fscrypt@vger.kernel.org, stable@vger.kernel.org, syzbot+ba9dac45bc76c490b7c3@syzkaller.appspotmail.com Subject: [PATCH] ext4: don't allow journal inode to have encrypt flag Date: Tue, 1 Nov 2022 22:33:12 -0700 Message-Id: <20221102053312.189962-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org From: Eric Biggers Mounting a filesystem whose journal inode has the encrypt flag causes a NULL dereference in fscrypt_limit_io_blocks() when the 'inlinecrypt' mount option is used. The problem is that when jbd2_journal_init_inode() calls bmap(), it eventually finds its way into ext4_iomap_begin(), which calls fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks() requires that if the inode is encrypted, then its encryption key must already be set up. That's not the case here, since the journal inode is never "opened" like a normal file would be. Hence the crash. A reproducer is: mkfs.ext4 -F /dev/vdb debugfs -w /dev/vdb -R "set_inode_field <8> flags 0x80808" mount /dev/vdb /mnt -o inlinecrypt To fix this, make ext4 consider journal inodes with the encrypt flag to be invalid. (Note, maybe other flags should be rejected on the journal inode too. For now, this is just the minimal fix for the above issue.) I've marked this as fixing the commit that introduced the call to fscrypt_limit_io_blocks(), since that's what made an actual crash start being possible. But this fix could be applied to any version of ext4 that supports the encrypt feature. Reported-by: syzbot+ba9dac45bc76c490b7c3@syzkaller.appspotmail.com Fixes: 38ea50daa7a4 ("ext4: support direct I/O with fscrypt using blk-crypto") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) base-commit: 8f71a2b3f435f29b787537d1abedaa7d8ebe6647 diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 7950904fbf04f..2274f730b87e5 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5723,7 +5723,7 @@ static struct inode *ext4_get_journal_inode(struct super_block *sb, ext4_debug("Journal inode found at %p: %lld bytes\n", journal_inode, journal_inode->i_size); - if (!S_ISREG(journal_inode->i_mode)) { + if (!S_ISREG(journal_inode->i_mode) || IS_ENCRYPTED(journal_inode)) { ext4_msg(sb, KERN_ERR, "invalid journal inode"); iput(journal_inode); return NULL;