[PATCH v2] phy: qcom-qusb2: Fix a memory leak on probe

[Vladimir Zapolskiy]

On success nvmem_cell_read() returns a pointer to a dynamically allocated
buffer, and therefore it shall be freed after usage.

The issue is reported by kmemleak:

  # cat /sys/kernel/debug/kmemleak
  unreferenced object 0xffff3b3803e4b280 (size 128):
    comm "kworker/u16:1", pid 107, jiffies 4294892861 (age 94.120s)
    hex dump (first 32 bytes):
      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    backtrace:
      [<000000007739afdc>] __kmalloc+0x27c/0x41c
      [<0000000071c0fbf8>] nvmem_cell_read+0x40/0xe0
      [<00000000e803ef1f>] qusb2_phy_init+0x258/0x5bc
      [<00000000fc81fcfa>] phy_init+0x70/0x110
      [<00000000e3d48a57>] dwc3_core_soft_reset+0x4c/0x234
      [<0000000027d1dbd4>] dwc3_core_init+0x68/0x990
      [<000000001965faf9>] dwc3_probe+0x4f4/0x730
      [<000000002f7617ca>] platform_probe+0x74/0xf0
      [<00000000a2576cac>] really_probe+0xc4/0x470
      [<00000000bc77f2c5>] __driver_probe_device+0x11c/0x190
      [<00000000130db71f>] driver_probe_device+0x48/0x110
      [<0000000019f36c2b>] __device_attach_driver+0xa4/0x140
      [<00000000e5812ff7>]  bus_for_each_drv+0x84/0xe0
      [<00000000f4bac574>] __device_attach+0xe4/0x1c0
      [<00000000d3beb631>] device_initial_probe+0x20/0x30
      [<000000008019b9db>] bus_probe_device+0xa4/0xb0

Fixes: ca04d9d3e1b1 ("phy: qcom-qusb2: New driver for QUSB2 PHY on Qcom chips")
Signed-off-by: Vladimir Zapolskiy <vladimir.zapolskiy at linaro.org>
---
Changes from v1 to v2:
* fixed a memory leak in case of reading a zero value and return,
* corrected the fixed commit, the memory leak is present before a rename.

 drivers/phy/qualcomm/phy-qcom-qusb2.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/phy/qualcomm/phy-qcom-qusb2.c b/drivers/phy/qualcomm/phy-qcom-qusb2.c
index 3c1d3b71c825..f1d97fbd1331 100644
--- a/drivers/phy/qualcomm/phy-qcom-qusb2.c
+++ b/drivers/phy/qualcomm/phy-qcom-qusb2.c
@@ -561,7 +561,7 @@ static void qusb2_phy_set_tune2_param(struct qusb2_phy *qphy)
 {
 	struct device *dev = &qphy->phy->dev;
 	const struct qusb2_phy_cfg *cfg = qphy->cfg;
-	u8 *val;
+	u8 *val, hstx_trim;
 
 	/* efuse register is optional */
 	if (!qphy->cell)
@@ -575,7 +575,13 @@ static void qusb2_phy_set_tune2_param(struct qusb2_phy *qphy)
 	 * set while configuring the phy.
 	 */
 	val = nvmem_cell_read(qphy->cell, NULL);
-	if (IS_ERR(val) || !val[0]) {
+	if (IS_ERR(val)) {
+		dev_dbg(dev, "failed to read a valid hs-tx trim value\n");
+		return;
+	}
+	hstx_trim = val[0];
+	kfree(val);
+	if (!hstx_trim) {
 		dev_dbg(dev, "failed to read a valid hs-tx trim value\n");
 		return;
 	}
@@ -583,12 +589,10 @@ static void qusb2_phy_set_tune2_param(struct qusb2_phy *qphy)
 	/* Fused TUNE1/2 value is the higher nibble only */
 	if (cfg->update_tune1_with_efuse)
 		qusb2_write_mask(qphy->base, cfg->regs[QUSB2PHY_PORT_TUNE1],
-				 val[0] << HSTX_TRIM_SHIFT,
-				 HSTX_TRIM_MASK);
+				 hstx_trim << HSTX_TRIM_SHIFT, HSTX_TRIM_MASK);
 	else
 		qusb2_write_mask(qphy->base, cfg->regs[QUSB2PHY_PORT_TUNE2],
-				 val[0] << HSTX_TRIM_SHIFT,
-				 HSTX_TRIM_MASK);
+				 hstx_trim << HSTX_TRIM_SHIFT, HSTX_TRIM_MASK);
 }
 
 static int qusb2_phy_set_mode(struct phy *phy,
-- 
2.33.0