linux-kernel - Re: [PATCH v4] soc: qcom: mdt_loader: Add Upperbounds check for program header access

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Message-ID: <y6em73mzbh47fzpgfvfsrypw5ktgt6zaqfujscaxkjuqivlxcr@vcke7w4omq7b>
Date: Tue, 13 Feb 2024 23:42:16 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Auditya Bhattaram <quic_audityab@...cinc.com>
Cc: konrad.dybcio@...aro.org, linux-arm-msm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v4] soc: qcom: mdt_loader: Add Upperbounds check for
 program header access

On Tue, Feb 13, 2024 at 01:30:10PM +0530, Auditya Bhattaram wrote:
> hash_index is evaluated by looping phdrs till QCOM_MDT_TYPE_HASH
> is found. Add an upperbound check to phdrs to access within elf size.
> 

How is this compatible with what is being observed on SM8450 and
implemented in commit 8bd42e2341a7 ("soc: qcom: mdt_loader: Allow hash
segment to be split out"?

Regards,
Bjorn

> Fixes: 64fb5eb87d58 ("soc: qcom: mdt_loader: Allow hash to reside in any segment")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Auditya Bhattaram <quic_audityab@...cinc.com>
> Acked-by: Mukesh Ojha <quic_mojha@...cinc.com>
> ---
> Changes in v4:
>  - Added additional prints incase of Invalid access.
> Link to v3 https://lore.kernel.org/stable/1c91c653-cebe-4407-bdd6-cfc73b64c0fb@quicinc.com
> Link to v2 https://lore.kernel.org/linux-arm-msm/9773d189-c896-d5c5-804c-e086c24987b4@quicinc.com/T/#t
> Link to v1 https://lore.kernel.org/linux-arm-msm/5d7a3b97-d840-4863-91a0-32c1d8e7532f@linaro.org/T/#t
> ---
>  drivers/soc/qcom/mdt_loader.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
> index 6f177e46fa0f..1a79a7bba468 100644
> --- a/drivers/soc/qcom/mdt_loader.c
> +++ b/drivers/soc/qcom/mdt_loader.c
> @@ -145,6 +143,13 @@ void *qcom_mdt_read_metadata(const struct firmware *fw, size_t *data_len,
>  	if (phdrs[0].p_type == PT_LOAD)
>  		return ERR_PTR(-EINVAL);
> 
> +	if (((size_t)(phdrs + ehdr->e_phnum)) > ((size_t)ehdr + fw->size)) {
> +		dev_err(dev,
> +			"Invalid phdrs access for fw: %s, e_phnum: %u, fw->size: %zu\n",
> +			fw_name, ehdr->e_phnum, fw->size);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
>  	for (i = 1; i < ehdr->e_phnum; i++) {
>  		if ((phdrs[i].p_flags & QCOM_MDT_TYPE_MASK) == QCOM_MDT_TYPE_HASH) {
>  			hash_segment = i;
> --
> 2.17.1
>