From patchwork Sat May 27 07:36:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe JAILLET X-Patchwork-Id: 13257555 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 26361C77B73 for ; Sat, 27 May 2023 07:44:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231178AbjE0HoL (ORCPT ); Sat, 27 May 2023 03:44:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231802AbjE0HoG (ORCPT ); Sat, 27 May 2023 03:44:06 -0400 Received: from smtp.smtpout.orange.fr (smtp-23.smtpout.orange.fr [80.12.242.23]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 87DD0B6 for ; Sat, 27 May 2023 00:44:05 -0700 (PDT) Received: from pop-os.home ([86.243.2.178]) by smtp.orange.fr with ESMTPA id 2oTXqn1098aX92oTYqO5DH; Sat, 27 May 2023 09:36:32 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wanadoo.fr; s=t20230301; t=1685172992; bh=jfcq+JgA5tqsNjhJdIRr8u+hc7+NPdvjx/XHhop2/Is=; h=From:To:Cc:Subject:Date; b=oP99AC7iTJ4UihSNEW/pzpRz9iPotcP9k/mZw954h9q8LA73LTHHJczpFnk/qBRMl lTgFns4cYPAN0ZS5x6mLvkGA9aHf/LGVs7PHK1WyQ8FgT/PZKljP8D+qV/VWCj7u1O y5T3byDZuJIiQbpJBgaR92HwVRQk/zMZXh293hilGGGDolrRYqEnnUFkcBH4y5uhzX OtG9D7FE7fw1Hosi0RDUdPhpi8F+sq2tb94BpW43lwxRQvXp28WrHCZ0geIHiwbcMM EjqY4iW+4nNJFKZbDd+TQdHrgZQFQnnyLnhnvL8JjrLtwL1J2V7JuMPHNCPcY7yrnF Pe4WX+B0QtlnA== X-ME-Helo: pop-os.home X-ME-Auth: Y2hyaXN0b3BoZS5qYWlsbGV0QHdhbmFkb28uZnI= X-ME-Date: Sat, 27 May 2023 09:36:32 +0200 X-ME-IP: 86.243.2.178 From: Christophe JAILLET To: vkoul@kernel.org Cc: dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET Subject: [PATCH v2] dmaengine: mcf-edma: Fix a potential un-allocated memory access Date: Sat, 27 May 2023 09:36:31 +0200 Message-Id: X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org When 'mcf_edma' is allocated, some space is allocated for a flexible array at the end of the struct. 'chans' item are allocated, that is to say 'pdata->dma_channels'. Then, this number of item is stored in 'mcf_edma->n_chans'. A few lines later, if 'mcf_edma->n_chans' is 0, then a default value of 64 is set. This ends to no space allocated by devm_kzalloc() because chans was 0, but 64 items are read and/or written in some not allocated memory. Change the logic to define a default value before allocating the memory. Fixes: e7a3ff92eaf1 ("dmaengine: fsl-edma: add ColdFire mcf5441x edma support") Signed-off-by: Christophe JAILLET --- If I'm correct, then: - the default value is hard-coded as 64. There is also a #define EDMA_CHANNELS 64 which maybe could be used, or renamed as EDMA_DEFAULT_CHANNELS - mcf_edma_err_handler() looks bogus, because it considers that mcf_edma->chans has EDMA_CHANNELS items. I guess that something related to mcf_edma->n_chans is what is expected, but how should this be done? Maybe, the EDMA_CHANNELS value should be used all the time? Maybe, the number of chans should be limited to EDMA_CHANNELS? Maybe, the number of chans should be at least EDMA_CHANNELS? Maybe, maybe, maybe, but me, I don't know :( All I know is that this patch compiles :) and that it can gives Dan an idea for smatch for checking access to un-allocated memory related to flexible array :) v2: I forgot the subject in v1... --- drivers/dma/mcf-edma.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/dma/mcf-edma.c b/drivers/dma/mcf-edma.c index ebd8733f72ad..9413fad08a60 100644 --- a/drivers/dma/mcf-edma.c +++ b/drivers/dma/mcf-edma.c @@ -190,7 +190,13 @@ static int mcf_edma_probe(struct platform_device *pdev) return -EINVAL; } - chans = pdata->dma_channels; + if (!pdata->dma_channels) { + dev_info(&pdev->dev, "setting default channel number to 64"); + chans = 64; + } else { + chans = pdata->dma_channels; + } + len = sizeof(*mcf_edma) + sizeof(*mcf_chan) * chans; mcf_edma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL); if (!mcf_edma) @@ -202,11 +208,6 @@ static int mcf_edma_probe(struct platform_device *pdev) mcf_edma->drvdata = &mcf_data; mcf_edma->big_endian = 1; - if (!mcf_edma->n_chans) { - dev_info(&pdev->dev, "setting default channel number to 64"); - mcf_edma->n_chans = 64; - } - mutex_init(&mcf_edma->fsl_edma_mutex); mcf_edma->membase = devm_platform_ioremap_resource(pdev, 0);