Re: [PATCH 3/3] nvmem: mtk-efuse: add mt6572 support

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Incorrect string comparison logic erroneously matches any nvmem cell name that is a prefix of 'gpu-speedbin'.
--

--- Patch [3]: [PATCH 3/3] nvmem: mtk-efuse: add mt6572 support ---
commit 2c71c19eb8895343bae32ea1c4c07b25c01cd56c
Author: Roman Vivchar <rva333@protonmail.com>

    nvmem: mtk-efuse: add mt6572 support
    
    Add a platform data struct for the efuse controller.

> diff --git a/drivers/nvmem/mtk-efuse.c b/drivers/nvmem/mtk-efuse.c
> index 1462f27608184..a794346084658 100644
> --- a/drivers/nvmem/mtk-efuse.c
> +++ b/drivers/nvmem/mtk-efuse.c
> @@ -124,6 +124,11 @@ static int mtk_efuse_probe(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static const struct mtk_efuse_pdata mtk_mt6572_efuse_pdata = {
> +	.uses_post_processing = false,

[Severity: High]
This isn't a bug introduced by this patch, but there is a pre-existing issue
with the post-processing logic in this driver.

Looking at mtk_efuse_fixup_dt_cell_info(), the string comparison logic
erroneously matches any nvmem cell name that is a prefix of "gpu-speedbin":

drivers/nvmem/mtk-efuse.c:mtk_efuse_fixup_dt_cell_info() {
    ...
	if (cell->nbits <= 3 &&
	    strncmp(cell->name, "gpu-speedbin", min(sz, strlen("gpu-speedbin"))) == 0)
		cell->read_post_process = mtk_efuse_gpu_speedbin_pp;
    ...
}

Because strncmp() uses min(strlen(cell->name), strlen("gpu-speedbin")) for
the comparison length, it restricts the comparison to the shorter length.

If a device tree defines a cell with a name that is a substring of
"gpu-speedbin" (e.g., "gpu" or "gpu-speed") and has 3 or fewer bits, this
will evaluate to 0.

This incorrectly applies the post-processing fixup to completely unrelated
cells, which could cause silent data corruption.

Would it be possible to change this comparison to prevent short-prefix
matches?

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260715-6572-nvmem-v1-0-9c13be99d077@protonmail.com?part=3