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

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Message-ID: <20250528194425.567172-2-krzysztof.kozlowski@linaro.org>
Date: Wed, 28 May 2025 21:44:26 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Lee Jones <lee@...nel.org>,
	Pavel Machek <pavel@...nel.org>,
	Fenglin Wu <quic_fenglinw@...cinc.com>,
	linux-leds@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
	stable@...r.kernel.org
Subject: [PATCH] leds: flash: leds-qcom-flash: Fix registry access after re-bind

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@...r.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>

---

This is a nice example why constifying static memory is useful.
---
 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),
+				    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);
-- 
2.45.2