linux-kernel - Re: [PATCH v2] iio: Fix uninitialized variable

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Message-ID: <26f2e35e-0a07-4b24-91a2-a48d4bc5dadc@gmail.com>
Date: Fri, 11 Oct 2024 14:31:00 +0200
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: "Yo-Jung (Leo) Lin" <0xff07@...il.com>
Cc: linux-kernel-mentees@...ts.linuxfoundation.org, ricardo@...liere.net,
 skhan@...uxfoundation.org, Jonathan Cameron <jic23@...nel.org>,
 Lars-Peter Clausen <lars@...afoo.de>, Nathan Chancellor <nathan@...nel.org>,
 Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling
 <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
 Vasileios Amoiridis <vassilisamir@...il.com>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Angel Iglesias <ang.iglesiasg@...il.com>, Adam Rizkalla
 <ajarizzo@...il.com>, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH v2] iio: Fix uninitialized variable

On 11/10/2024 13:52, Yo-Jung (Leo) Lin wrote:
> clang found that the "offset" in bmp580_trigger_handler doesn't get
> initialized before access. Add proper initialization to this variable.
> 
> Signed-off-by: Yo-Jung (Leo) Lin <0xff07@...il.com>
> ---
> Change in v2:
> - Make value initialization immediate before its first use.
> - Link to v1: https://lore.kernel.org/all/20241011093752.30685-1-0xff07@gmail.com/
> 
> ---
>  drivers/iio/pressure/bmp280-core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index f4df222ed0c3..682329f81886 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -2222,6 +2222,8 @@ static irqreturn_t bmp580_trigger_handler(int irq, void *p)
>  		goto out;
>  	}
>  
> +	offset = 0;
> +
>  	/* Pressure calculations */
>  	memcpy(&data->sensor_data[offset], &data->buf[3], 3);
>  

That was a quick reply. I would recommend you to wait a little bit while
the first version is under discussion.

I still see the offset thing a bit weird. data->sensor_data uses an
offset to avoid hard-coded numbers, but for data->buf we do exactly
that, in the very same lines.

Setting offset to 0 to access the first element i.e. no offset required,
and then adding the actual offset sizeof(s32), which could even be a
const if the first access was to sensor_data[0], looks to verbose.

These things are of course not critical, and the proposed fix is
definitely ok, but I am missing some consistency here.