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=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 05515C2B9F4 for ; Mon, 14 Jun 2021 11:27:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3D1861019 for ; Mon, 14 Jun 2021 11:27:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235427AbhFNL3B (ORCPT ); Mon, 14 Jun 2021 07:29:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:45448 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234266AbhFNLOL (ORCPT ); Mon, 14 Jun 2021 07:14:11 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6541B6145B; Mon, 14 Jun 2021 10:49:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623667743; bh=qvfO6rWQb7mAwjSIEGjJoAIEmSpD/qlH9Ekye5y9Tew=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q5VEC55CIUCYKkVYQGvju0T9/F0eBdkqIrDJN6ZSW0PqsPUThczkeOnLBZ9m6q2Ic xYtEju/MP7fCm4cnHqimYxIKlncMLSXYd6CjuqOql8+qDIBYCBKw5MHFcCVajaTI6H 6wKy/E3ZzcYOCIXMf26Bm3v10hgALuhqb9rWkSZg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joe Burmeister , Lukas Wunner , Phil Elwell , Mark Brown Subject: [PATCH 5.12 056/173] spi: bcm2835: Fix out-of-bounds access with more than 4 slaves Date: Mon, 14 Jun 2021 12:26:28 +0200 Message-Id: <20210614102700.018037636@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210614102658.137943264@linuxfoundation.org> References: <20210614102658.137943264@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: Lukas Wunner commit 13817d466eb8713a1ffd254f537402f091d48444 upstream. Commit 571e31fa60b3 ("spi: bcm2835: Cache CS register value for ->prepare_message()") limited the number of slaves to 3 at compile-time. The limitation was necessitated by a statically-sized array prepare_cs[] in the driver private data which contains a per-slave register value. The commit sought to enforce the limitation at run-time by setting the controller's num_chipselect to 3: Slaves with a higher chipselect are rejected by spi_add_device(). However the commit neglected that num_chipselect only limits the number of *native* chipselects. If GPIO chipselects are specified in the device tree for more than 3 slaves, num_chipselect is silently raised by of_spi_get_gpio_numbers() and the result are out-of-bounds accesses to the statically-sized array prepare_cs[]. As a bandaid fix which is backportable to stable, raise the number of allowed slaves to 24 (which "ought to be enough for anybody"), enforce the limitation on slave ->setup and revert num_chipselect to 3 (which is the number of native chipselects supported by the controller). An upcoming for-next commit will allow an arbitrary number of slaves. Fixes: 571e31fa60b3 ("spi: bcm2835: Cache CS register value for ->prepare_message()") Reported-by: Joe Burmeister Signed-off-by: Lukas Wunner Cc: stable@vger.kernel.org # v5.4+ Cc: Phil Elwell Link: https://lore.kernel.org/r/75854affc1923309fde05e47494263bde73e5592.1621703210.git.lukas@wunner.de Signed-off-by: Mark Brown Signed-off-by: Greg Kroah-Hartman --- drivers/spi/spi-bcm2835.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -68,7 +68,7 @@ #define BCM2835_SPI_FIFO_SIZE 64 #define BCM2835_SPI_FIFO_SIZE_3_4 48 #define BCM2835_SPI_DMA_MIN_LENGTH 96 -#define BCM2835_SPI_NUM_CS 4 /* raise as necessary */ +#define BCM2835_SPI_NUM_CS 24 /* raise as necessary */ #define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \ | SPI_NO_CS | SPI_3WIRE) @@ -1195,6 +1195,12 @@ static int bcm2835_spi_setup(struct spi_ struct gpio_chip *chip; u32 cs; + if (spi->chip_select >= BCM2835_SPI_NUM_CS) { + dev_err(&spi->dev, "only %d chip-selects supported\n", + BCM2835_SPI_NUM_CS - 1); + return -EINVAL; + } + /* * Precalculate SPI slave's CS register value for ->prepare_message(): * The driver always uses software-controlled GPIO chip select, hence @@ -1288,7 +1294,7 @@ static int bcm2835_spi_probe(struct plat ctlr->use_gpio_descriptors = true; ctlr->mode_bits = BCM2835_SPI_MODE_BITS; ctlr->bits_per_word_mask = SPI_BPW_MASK(8); - ctlr->num_chipselect = BCM2835_SPI_NUM_CS; + ctlr->num_chipselect = 3; ctlr->setup = bcm2835_spi_setup; ctlr->transfer_one = bcm2835_spi_transfer_one; ctlr->handle_err = bcm2835_spi_handle_err;