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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 02731C43603 for ; Tue, 17 Dec 2019 23:57:32 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 5149720729 for ; Tue, 17 Dec 2019 23:57:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="PGch8hly" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5149720729 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17505-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 15594 invoked by uid 550); 17 Dec 2019 23:57:24 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 15560 invoked from network); 17 Dec 2019 23:57:24 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=98nQRWslLAdLJGWLqVhnniGfUUsPCo+VqaOoUSaSUns=; b=PGch8hlyMzS3H+pj7vsa+6bP67QROcjbgUjWjaiomnK918y2/7P+cQB1j6ACFDOLFj wNbtp61480FQ7nbl2qR39dcoMTxq+SEHu9B7vXPmoZ1IfJNKL4AIrwBCeCkvI4AWc0tV xfJSmgOcLHPXwvOXwxPWyaho6pWx92dPSHWYk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=98nQRWslLAdLJGWLqVhnniGfUUsPCo+VqaOoUSaSUns=; b=ruAfFpvDKTAYYDSQ9cIIfIe6+gn0nP/5pyieFPuP93B7l0A8ZuT5JE50BXK02PXEHF TCgq1pvDAtHGmnhNbSQi33NDMCHpvmvWtY1pKdUNdazm88m/0SB8zQdmvLGFp7jVFy8r 7NlG5HeLUF/MU3zZQ3Kz/lu1XvudIlQsko5ttXfOTAlbA736i6PyEAp0Uoz8jmkvxeKN tpg1qPSmAorxxb3qTtmPTb37Gj6w14oHd7zhJXYrMklwFe9T9jqHQ7gu5Egtd9IJMNFd IMMr4ouUASAe63+vcw2JJ9t8hTXTeiWIqEK+v7flO6qf+8N+R938SUiyS7B0hCCLNZB0 7HWw== X-Gm-Message-State: APjAAAWXOkzk/jO6r1uv5jDLzlYN29MqBIlHX7aoGBkd4nxX1aW75rBt 4pNhZPYeVSNQ6MWlvxP4Bqfs5A== X-Google-Smtp-Source: APXvYqwtElBq8KfVRNF9PP7xPPEpVIg/BmDDCfZjjfZ0McuBDEedfKzOjWDThbCPUdUTzVobikP7tg== X-Received: by 2002:a17:90a:8a8f:: with SMTP id x15mr114462pjn.87.1576627031671; Tue, 17 Dec 2019 15:57:11 -0800 (PST) Date: Tue, 17 Dec 2019 15:57:09 -0800 From: Kees Cook To: Tianlin Li Cc: kernel-hardening@lists.openwall.com, Arnd Bergmann , Greg Kroah-Hartman , linux-kernel@vger.kernel.org Subject: Re: [PATCH] drivers/misc: have the callers of set_memory_*() check the return value Message-ID: <201912171557.507D9D2@keescook> References: <20191217194528.16461-1-tli@digitalocean.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191217194528.16461-1-tli@digitalocean.com> On Tue, Dec 17, 2019 at 01:45:28PM -0600, Tianlin Li wrote: > Right now several architectures allow their set_memory_*() family of > functions to fail, but callers may not be checking the return values. > If set_memory_*() returns with an error, call-site assumptions may be > infact wrong to assume that it would either succeed or not succeed at > all. Ideally, the failure of set_memory_*() should be passed up the > call stack, and callers should examine the failure and deal with it. > > Need to fix the callers and add the __must_check attribute. They also > may not provide any level of atomicity, in the sense that the memory > protections may be left incomplete on failure. This issue likely has a > few steps on effects architectures: > 1)Have all callers of set_memory_*() helpers check the return value. > 2)Add __must_check to all set_memory_*() helpers so that new uses do > not ignore the return value. > 3)Add atomicity to the calls so that the memory protections aren't left > in a partial state. > > This series is part of step 1. Make sram driver check the return value of > set_memory_*(). > > Signed-off-by: Tianlin Li Reviewed-by: Kees Cook -Kees > --- > drivers/misc/sram-exec.c | 21 +++++++++++++++++---- > 1 file changed, 17 insertions(+), 4 deletions(-) > > diff --git a/drivers/misc/sram-exec.c b/drivers/misc/sram-exec.c > index d054e2842a5f..cb57ac6ab4c3 100644 > --- a/drivers/misc/sram-exec.c > +++ b/drivers/misc/sram-exec.c > @@ -85,6 +85,7 @@ void *sram_exec_copy(struct gen_pool *pool, void *dst, void *src, > unsigned long base; > int pages; > void *dst_cpy; > + int ret; > > mutex_lock(&exec_pool_list_mutex); > list_for_each_entry(p, &exec_pool_list, list) { > @@ -104,16 +105,28 @@ void *sram_exec_copy(struct gen_pool *pool, void *dst, void *src, > > mutex_lock(&part->lock); > > - set_memory_nx((unsigned long)base, pages); > - set_memory_rw((unsigned long)base, pages); > + ret = set_memory_nx((unsigned long)base, pages); > + if (ret) > + goto error_out; > + ret = set_memory_rw((unsigned long)base, pages); > + if (ret) > + goto error_out; > > dst_cpy = fncpy(dst, src, size); > > - set_memory_ro((unsigned long)base, pages); > - set_memory_x((unsigned long)base, pages); > + ret = set_memory_ro((unsigned long)base, pages); > + if (ret) > + goto error_out; > + ret = set_memory_x((unsigned long)base, pages); > + if (ret) > + goto error_out; > > mutex_unlock(&part->lock); > > return dst_cpy; > + > +error_out: > + mutex_unlock(&part->lock); > + return NULL; > } > EXPORT_SYMBOL_GPL(sram_exec_copy); > -- > 2.17.1 > -- Kees Cook