Re: [PATCH] leds: flash: leds-qcom-flash: Fix registry access after re-bind

[Fenglin Wu <fenglin.wu@oss.qualcomm.com>]

On 5/29/2025 3:44 AM, Krzysztof Kozlowski wrote:
> Driver in probe() updates each of 'reg_field' with 'reg_base':
> 
> 	for (i = 0; i < REG_MAX_COUNT; i++)
> 		regs[i].reg += reg_base;
> 
> 'reg_field' array (under variable 'regs' above) is statically allocated,
> this each re-bind would add another 'reg_base' leading to bogus
> register addresses.  Constify the local 'reg_field' array and duplicate
> it in probe to solve this.
> 
> Fixes: 96a2e242a5dc ("leds: flash: Add driver to support flash LED module in QCOM PMICs")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 
> ---
> 
> This is a nice example why constifying static memory is useful.

Thanks for fixing it!

> ---
>   drivers/leds/flash/leds-qcom-flash.c | 15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/leds/flash/leds-qcom-flash.c b/drivers/leds/flash/leds-qcom-flash.c
> index b4c19be51c4d..b8a48c15d797 100644
> --- a/drivers/leds/flash/leds-qcom-flash.c
> +++ b/drivers/leds/flash/leds-qcom-flash.c
> @@ -117,7 +117,7 @@ enum {
>   	REG_MAX_COUNT,
>   };
>   
> -static struct reg_field mvflash_3ch_regs[REG_MAX_COUNT] = {
> +static const struct reg_field mvflash_3ch_regs[REG_MAX_COUNT] = {
>   	REG_FIELD(0x08, 0, 7),			/* status1	*/
>   	REG_FIELD(0x09, 0, 7),                  /* status2	*/
>   	REG_FIELD(0x0a, 0, 7),                  /* status3	*/
> @@ -132,7 +132,7 @@ static struct reg_field mvflash_3ch_regs[REG_MAX_COUNT] = {
>   	REG_FIELD(0x58, 0, 2),			/* therm_thrsh3 */
>   };
>   
> -static struct reg_field mvflash_4ch_regs[REG_MAX_COUNT] = {
> +static const struct reg_field mvflash_4ch_regs[REG_MAX_COUNT] = {
>   	REG_FIELD(0x06, 0, 7),			/* status1	*/
>   	REG_FIELD(0x07, 0, 6),			/* status2	*/
>   	REG_FIELD(0x09, 0, 7),			/* status3	*/
> @@ -854,11 +854,17 @@ static int qcom_flash_led_probe(struct platform_device *pdev)
>   	if (val == FLASH_SUBTYPE_3CH_PM8150_VAL || val == FLASH_SUBTYPE_3CH_PMI8998_VAL) {
>   		flash_data->hw_type = QCOM_MVFLASH_3CH;
>   		flash_data->max_channels = 3;
> -		regs = mvflash_3ch_regs;
> +		regs = devm_kmemdup(dev, mvflash_3ch_regs, sizeof(mvflash_3ch_regs),
> +				    GFP_KERNEL);
> +		if (!regs)
> +			return -ENOMEM;
>   	} else if (val == FLASH_SUBTYPE_4CH_VAL) {
>   		flash_data->hw_type = QCOM_MVFLASH_4CH;
>   		flash_data->max_channels = 4;
> -		regs = mvflash_4ch_regs;
> +		regs = devm_kmemdup(dev, mvflash_4ch_regs, sizeof(mvflash_3ch_regs),

Minor: sizeof(mvflash_4ch_regs)

> +				    GFP_KERNEL);
> +		if (!regs)
> +			return -ENOMEM;
>   
>   		rc = regmap_read(regmap, reg_base + FLASH_REVISION_REG, &val);
>   		if (rc < 0) {
> @@ -880,6 +886,7 @@ static int qcom_flash_led_probe(struct platform_device *pdev)
>   		dev_err(dev, "Failed to allocate regmap field, rc=%d\n", rc);
>   		return rc;
>   	}
> +	devm_kfree(dev, regs); /* devm_regmap_field_bulk_alloc() makes copies */
>   
>   	platform_set_drvdata(pdev, flash_data);
>   	mutex_init(&flash_data->lock);