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

From: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
To: Vinod Koul <vkoul@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>,
	Andy Gross <agross@kernel.org>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Vivek Gautam <vivek.gautam@codeaurora.org>,
	linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org
Subject: Re: [PATCH v2] phy: qcom-qusb2: Fix a memory leak on probe
Date: Fri, 1 Oct 2021 14:04:06 +0300	[thread overview]
Message-ID: <56c4530b-2f66-f325-b703-e58e90c3c66a@linaro.org> (raw)
In-Reply-To: <YVbYDIUdyTQD6gXq@matsya>

On 10/1/21 12:42 PM, Vinod Koul wrote:
> On 23-09-21, 02:35, Vladimir Zapolskiy wrote:
>> 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@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");
> 
> not an error log..?
> 

It's a copy from the existing code, no changes on error but the memory leak fix.

If CONFIG_NVMEM is not set, then nvmem_cell_read() returns ERR_PTR(-EOPNOTSUPP),
still it allows to build/run the phy driver, so it seems to be a valid option,
please correct me.

--
Best wishes,
Vladimir