Re: [PATCH v2 2/2] mtd: nand: qpic_common: prevent out of bounds access of BAM arrays

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Gabor Juhos <j4g8y7@gmail.com>
Cc: Mark Brown <broonie@kernel.org>,
	 Md Sadre Alam <quic_mdalam@quicinc.com>,
	 Varadarajan Narayanan <quic_varada@quicinc.com>,
	 Sricharan Ramabadhran <quic_srichara@quicinc.com>,
	 Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	 linux-spi@vger.kernel.org, linux-mtd@lists.infradead.org,
	 linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	 Lakshmi Sowjanya D <quic_laksd@quicinc.com>
Subject: Re: [PATCH v2 2/2] mtd: nand: qpic_common: prevent out of bounds access of BAM arrays
Date: Mon, 02 Jun 2025 15:53:08 +0200	[thread overview]
Message-ID: <87iklep7wb.fsf@bootlin.com> (raw)
In-Reply-To: <20250529-qpic-snand-avoid-mem-corruption-v2-2-2f0d13afc7d2@gmail.com> (Gabor Juhos's message of "Thu, 29 May 2025 19:25:11 +0200")

Hello,

On 29/05/2025 at 19:25:11 +02, Gabor Juhos <j4g8y7@gmail.com> wrote:

> The common QPIC code does not do any boundary checking when it handles
> the command elements and scatter gater list arrays of a BAM transaction,
> thus it allows to access out of bounds elements in those.
>
> Although it is the responsibility of the given driver to allocate enough
> space for all possible BAM transaction variations, however there can be
> mistakes in the driver code which can lead to hidden memory corruption
> issues which are hard to debug.
>
> This kind of problem has been observed during testing the 'spi-qpic-snand'
> driver. Although the driver has been fixed with a preceding patch, but it
> still makes sense to reduce the chance of having such errors again later.
>
> In order to prevent such errors, change the qcom_alloc_bam_transaction()
> function to store the number of elements of the arrays in the
> 'bam_transaction' strucutre during allocation. Also, add sanity checks to
> the qcom_prep_bam_dma_desc_{cmd,data}() functions to avoid using out of
> bounds indices for the arrays.
>
> Tested-by: Lakshmi Sowjanya D <quic_laksd@quicinc.com>     # on SDX75
> Signed-off-by: Gabor Juhos <j4g8y7@gmail.com>

I'm fine with this patch going through spi,

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

Thanks,
Miquèl