From mboxrd@z Thu Jan 1 00:00:00 1970 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 22FE0C63699 for ; Tue, 27 Oct 2020 17:20:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C72A022202 for ; Tue, 27 Oct 2020 17:20:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603819247; bh=UnlBI+gDGXaX3+z9SxabEFOzl99bud+KBkDUDoIRtFU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=n2lR6bm2UP4MVgyB7+Ur9D3c8QfXpxICmzGUR83UAy3ruMNx8RYqmCt9acAl+5oWF u5/sVlx/JF2z91jw1f5JXOvoxgkkzsAUiZZGbkT7DKN8vZvKcvTdrB5sR48ptll8LO MAabMsBcnlx43IBq6fqPIDRO6y5Al4ABdWklyT4U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1818091AbgJ0RRY (ORCPT ); Tue, 27 Oct 2020 13:17:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:59126 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1783176AbgJ0O56 (ORCPT ); Tue, 27 Oct 2020 10:57:58 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EAD2E206F4; Tue, 27 Oct 2020 14:57:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603810677; bh=UnlBI+gDGXaX3+z9SxabEFOzl99bud+KBkDUDoIRtFU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D+TRTMvEsjekrrbXqV8FQMfmU6hYSO1XZL760I2JtkfNvYOYxHX0x05102FRs8VAX fTZvvKtO2K3Z/DDEvnVnDB79IHJkpwRklT307Rqsdh0uvqLXWsdwfbZ9dvLmtBqkAH 5LQj+9bqcFELCbw+Kb1AkRK12DjG5b/Et7wyAv4E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, KP Singh , Florent Revest , Mimi Zohar , Sasha Levin Subject: [PATCH 5.8 225/633] ima: Fix NULL pointer dereference in ima_file_hash Date: Tue, 27 Oct 2020 14:49:28 +0100 Message-Id: <20201027135533.237888356@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135522.655719020@linuxfoundation.org> References: <20201027135522.655719020@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: KP Singh [ Upstream commit aa662fc04f5b290b3979332588bf8d812b189962 ] ima_file_hash can be called when there is no iint->ima_hash available even though the inode exists in the integrity cache. It is fairly common for a file to not have a hash. (e.g. an mknodat, prior to the file being closed). Another example where this can happen (suggested by Jann Horn): Process A does: while(1) { unlink("/tmp/imafoo"); fd = open("/tmp/imafoo", O_RDWR|O_CREAT|O_TRUNC, 0700); if (fd == -1) { perror("open"); continue; } write(fd, "A", 1); close(fd); } and Process B does: while (1) { int fd = open("/tmp/imafoo", O_RDONLY); if (fd == -1) continue; char *mapping = mmap(NULL, 0x1000, PROT_READ|PROT_EXEC, MAP_PRIVATE, fd, 0); if (mapping != MAP_FAILED) munmap(mapping, 0x1000); close(fd); } Due to the race to get the iint->mutex between ima_file_hash and process_measurement iint->ima_hash could still be NULL. Fixes: 6beea7afcc72 ("ima: add the ability to query the cached hash of a given file") Signed-off-by: KP Singh Reviewed-by: Florent Revest Signed-off-by: Mimi Zohar Signed-off-by: Sasha Levin --- security/integrity/ima/ima_main.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index c1583d98c5e50..0b8f17570f210 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -531,6 +531,16 @@ int ima_file_hash(struct file *file, char *buf, size_t buf_size) return -EOPNOTSUPP; mutex_lock(&iint->mutex); + + /* + * ima_file_hash can be called when ima_collect_measurement has still + * not been called, we might not always have a hash. + */ + if (!iint->ima_hash) { + mutex_unlock(&iint->mutex); + return -EOPNOTSUPP; + } + if (buf) { size_t copied_size; -- 2.25.1