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Subject: Re: [PATCH v1 1/1] fpga: m10bmc-sec: Fix possible memory leak of
 flash_buf
To:     Russ Weight <russell.h.weight@intel.com>, mdf@kernel.org,
        hao.wu@intel.com, yilun.xu@intel.com, linux-fpga@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     lgoncalv@redhat.com, marpagan@redhat.com,
        matthew.gerlach@linux.intel.com,
        basheer.ahmed.muddebihal@intel.com, tianfei.zhang@intel.com,
        kernel test robot <lkp@intel.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        stable@vger.kernel.org
References: <20220916235205.106873-1-russell.h.weight@intel.com>
From:   Tom Rix <trix@redhat.com>
Message-ID: <f1e92634-8f96-6a3b-52e9-e83fa879ca39@redhat.com>
Date:   Fri, 16 Sep 2022 17:20:43 -0700
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On 9/16/22 4:52 PM, Russ Weight wrote:
> There is an error check following the allocation of flash_buf that returns
> without freeing flash_buf. It makes more sense to do the error check
> before the allocation and the reordering eliminates the memory leak.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Fixes: 154afa5c31cd ("fpga: m10bmc-sec: expose max10 flash update count")
> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Reviewed-by: Tom Rix <trix@redhat.com>
> Cc: <stable@vger.kernel.org>
> ---
>   drivers/fpga/intel-m10-bmc-sec-update.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/fpga/intel-m10-bmc-sec-update.c b/drivers/fpga/intel-m10-bmc-sec-update.c
> index 526c8cdd1474..79d48852825e 100644
> --- a/drivers/fpga/intel-m10-bmc-sec-update.c
> +++ b/drivers/fpga/intel-m10-bmc-sec-update.c
> @@ -148,10 +148,6 @@ static ssize_t flash_count_show(struct device *dev,
>   	stride = regmap_get_reg_stride(sec->m10bmc->regmap);
>   	num_bits = FLASH_COUNT_SIZE * 8;
>   
> -	flash_buf = kmalloc(FLASH_COUNT_SIZE, GFP_KERNEL);
> -	if (!flash_buf)
> -		return -ENOMEM;
> -
>   	if (FLASH_COUNT_SIZE % stride) {
>   		dev_err(sec->dev,
>   			"FLASH_COUNT_SIZE (0x%x) not aligned to stride (0x%x)\n",
> @@ -160,6 +156,10 @@ static ssize_t flash_count_show(struct device *dev,
>   		return -EINVAL;
>   	}
>   
> +	flash_buf = kmalloc(FLASH_COUNT_SIZE, GFP_KERNEL);
> +	if (!flash_buf)
> +		return -ENOMEM;
> +
>   	ret = regmap_bulk_read(sec->m10bmc->regmap, STAGING_FLASH_COUNT,
>   			       flash_buf, FLASH_COUNT_SIZE / stride);
>   	if (ret) {