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[23.128.96.18]) by mx.google.com with ESMTP id p3si11025741edr.444.2021.06.14.03.59.31; Mon, 14 Jun 2021 03:59:54 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b="jpdyiCr/"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234853AbhFNK7U (ORCPT + 99 others); Mon, 14 Jun 2021 06:59:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:58492 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234086AbhFNKus (ORCPT ); Mon, 14 Jun 2021 06:50:48 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 42A0661465; Mon, 14 Jun 2021 10:38:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623667127; bh=Q98+R8IUxy/p1FVfUojjPrz1bvHZhgEql2cyV/zAHfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jpdyiCr/fQD78WGihafFHhaagPgXm6VCqHYrNWvqjy1wvqGkaZ0/w6ZUlDAICHYm2 otwGsjaiOBdnNlCcZI4M/X4lXvNb38hzIMmHxmZNZohr5LKV8m4lbHtZrrk2YyH5sE yx+G01KIs0McFeszA/5vq3Em8M0Hbp/hcZHO/0DA= 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 5.4 38/84] spi: bcm2835: Fix out-of-bounds access with more than 4 slaves Date: Mon, 14 Jun 2021 12:27:16 +0200 Message-Id: <20210614102647.661444811@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210614102646.341387537@linuxfoundation.org> References: <20210614102646.341387537@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 3 /* 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) @@ -1181,6 +1181,12 @@ 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 @@ -1274,7 +1280,7 @@ 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;