linux-kernel - Re: [PATCH 1/3] nvmem: sprd: Fix memory overflow issue during memcpy operation in efuse driver

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Message-ID: <296be5ed-47a6-4701-a7f5-968e9e65b5f8@linaro.org>
Date:   Fri, 8 Dec 2023 11:41:10 +0000
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Yanxin Huang <yanxin.huang@...soc.com>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Chunyan Zhang <zhang.lyra@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        huang yanxin <yanxin.huang07@...il.com>,
        Wenming Wu <wenming.wu@...soc.com>
Subject: Re: [PATCH 1/3] nvmem: sprd: Fix memory overflow issue during memcpy
 operation in efuse driver

thanks for the patch.

On 08/12/2023 06:11, Yanxin Huang wrote:
> The efuse driver didn't determine the size of bytes, resulting in memory
> overflow during memcpy operation.
> 
> Fixes: 096030e7f449 ("nvmem: sprd: Add Spreadtrum SoCs eFuse support")

Please add CC Stable for all the fixes.

> Signed-off-by: Yanxin Huang <yanxin.huang@...soc.com>
> ---
>   drivers/nvmem/sprd-efuse.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/nvmem/sprd-efuse.c b/drivers/nvmem/sprd-efuse.c
> index bb3105f3291f..24b63620d217 100644
> --- a/drivers/nvmem/sprd-efuse.c
> +++ b/drivers/nvmem/sprd-efuse.c
> @@ -311,6 +311,7 @@ static int sprd_efuse_read(void *context, u32 offset, void *val, size_t bytes)
>   	ret = sprd_efuse_raw_read(efuse, index, &data, blk_double);
>   	if (!ret) {
>   		data >>= blk_offset;
> +		bytes = bytes > sizeof(data) ? sizeof(data) : bytes;

looks like sprd_efuse_read is only reading upto 4 bytes max, and 
silently ignoring reading requests data after 4 bytes.

Is this working because consumers so far only requested 4 bytes and less ?
does dumping nvmem sysfs actually show real content in your case?

--srini
>   		memcpy(val, &data, bytes);


>   	}
>