linux-kernel - Re: [PATCH] pata_lagacy: Handle failed ATA timing computation in opti82c46x_set

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Date:   Wed, 18 Oct 2023 08:36:48 +0900
From:   Damien Le Moal <dlemoal@...nel.org>
To:     Haonan Li <lihaonan1105@...il.com>,
        Sergey Shtylyov <s.shtylyov@....ru>, linux-ide@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pata_lagacy: Handle failed ATA timing computation in
 opti82c46x_set_piomode

On 10/18/23 08:32, Haonan Li wrote:
> The function opti82c46x_set_piomode utilizes the ata_timing_compute()
> to determine the appropriate ATA timings for a given device. However,
> in certain conditions where the ata_timing_find_mode() function does
> not find a valid mode, ata_timing_compute() returns an error (-EINVAL),
> leaving the tp struct uninitialized.
> 
> This patch checks the return value of ata_timing_compute().
> This avoids any potential use of uninitialized `tp` struct in the
> opti82c46x_set_piomode function.
> 
> Signed-off-by: Haonan Li <lihaonan1105@...il.com>
> ---
>  drivers/ata/pata_legacy.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ata/pata_legacy.c b/drivers/ata/pata_legacy.c
> index 448a511cb..d94c365cb 100644
> --- a/drivers/ata/pata_legacy.c
> +++ b/drivers/ata/pata_legacy.c
> @@ -579,12 +579,16 @@ static void opti82c46x_set_piomode(struct ata_port *ap, struct ata_device *adev)
>  	clock = 1000000000 / khz[sysclk];
>  
>  	/* Get the timing data in cycles */
> -	ata_timing_compute(adev, adev->pio_mode, &t, clock, 1000);
> +	if (ata_timing_compute(adev, adev->pio_mode, &t, clock, 1000)) {
> +		return;
> +	}

You need a message here to tell the user something is wrong. See pata_amd.c for
an example.

>  
>  	/* Setup timing is shared */
>  	if (pair) {
>  		struct ata_timing tp;
> -		ata_timing_compute(pair, pair->pio_mode, &tp, clock, 1000);
> +		if (ata_timing_compute(pair, pair->pio_mode, &tp, clock, 1000)) {
> +			return;
> +		}

Same here. And while at it, please add a blank line after the declaration and
before your change.

>  
>  		ata_timing_merge(&t, &tp, &t, ATA_TIMING_SETUP);
>  	}

-- 
Damien Le Moal
Western Digital Research