From patchwork Thu Sep 16 20:34:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 12500227 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C3A5C4332F for ; Thu, 16 Sep 2021 20:35:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6333E6120F for ; Thu, 16 Sep 2021 20:35:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239130AbhIPUhO (ORCPT ); Thu, 16 Sep 2021 16:37:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:48510 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231982AbhIPUhM (ORCPT ); Thu, 16 Sep 2021 16:37:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 394F160FBF; Thu, 16 Sep 2021 20:35:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631824551; bh=PgkVBzwC/ElfXlh5G/WjU2Sucs8A8+5pZ7/S6pKmdvc=; h=From:To:Cc:Subject:Date:From; b=S05PLZ3Ug1VUZPyP8Tqz0L3jYQOb4tg2H+n7QsqWn3LhYq5w2WtN3XMVO0MayhNtl h561fJniEhuHaJOvm0mR3W93Bq6xmn7N1ANrACBs97eK0f5cAsAtHnlwxg8F+iUDiL qRMY1+8SQfAX//IqmtP6iAvKRj5EbcTxtX6qRinhEuhIwCe1ltMK2AHIb0qPMOO49U rtUZDC31+DPye3+ss45HosYFv28uaV27YEjGPHR+zWuD+MnClIr/E7uwUiw5r5sBWk lb9KZXWKk/TmexuiXwNNMNdxH2oaGz7oCwzgZkCXOE3B05BGJsCtT7UI/yMrpU4muG qbgc6IOtAhGmw== From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-btrfs@vger.kernel.org, stable@vger.kernel.org, Boris Burkov Subject: [PATCH] fs-verity: fix signed integer overflow with i_size near S64_MAX Date: Thu, 16 Sep 2021 13:34:24 -0700 Message-Id: <20210916203424.113376-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Eric Biggers If the file size is almost S64_MAX, the calculated number of Merkle tree levels exceeds FS_VERITY_MAX_LEVELS, causing FS_IOC_ENABLE_VERITY to fail. This is unintentional, since as the comment above the definition of FS_VERITY_MAX_LEVELS states, it is enough for over U64_MAX bytes of data using SHA-256 and 4K blocks. (Specifically, 4096*128**8 >= 2**64.) The bug is actually that when the number of blocks in the first level is calculated from i_size, there is a signed integer overflow due to i_size being signed. Fix this by treating i_size is unsigned. This was found by the new test "generic: test fs-verity EFBIG scenarios" (https://lkml.kernel.org/r/b1d116cd4d0ea74b9cd86f349c672021e005a75c.1631558495.git.boris@bur.io). This didn't affect ext4 or f2fs since those have a smaller maximum file size, but it did affect btrfs which allows files up to S64_MAX bytes. Reported-by: Boris Burkov Fixes: 3fda4c617e84 ("fs-verity: implement FS_IOC_ENABLE_VERITY ioctl") Fixes: fd2d1acfcadf ("fs-verity: add the hook for file ->open()") Cc: # v5.4+ Signed-off-by: Eric Biggers Reviewed-by: Boris Burkov --- fs/verity/enable.c | 2 +- fs/verity/open.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/verity/enable.c b/fs/verity/enable.c index 77e159a0346b1..60a4372aa4d75 100644 --- a/fs/verity/enable.c +++ b/fs/verity/enable.c @@ -177,7 +177,7 @@ static int build_merkle_tree(struct file *filp, * (level 0) and ascending to the root node (level 'num_levels - 1'). * Then at the end (level 'num_levels'), calculate the root hash. */ - blocks = (inode->i_size + params->block_size - 1) >> + blocks = ((u64)inode->i_size + params->block_size - 1) >> params->log_blocksize; for (level = 0; level <= params->num_levels; level++) { err = build_merkle_tree_level(filp, level, blocks, params, diff --git a/fs/verity/open.c b/fs/verity/open.c index 60ff8af7219fe..92df87f5fa388 100644 --- a/fs/verity/open.c +++ b/fs/verity/open.c @@ -89,7 +89,7 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params, */ /* Compute number of levels and the number of blocks in each level */ - blocks = (inode->i_size + params->block_size - 1) >> log_blocksize; + blocks = ((u64)inode->i_size + params->block_size - 1) >> log_blocksize; pr_debug("Data is %lld bytes (%llu blocks)\n", inode->i_size, blocks); while (blocks > 1) { if (params->num_levels >= FS_VERITY_MAX_LEVELS) {