linux-kernel - Re: [PATCH] mtd: parsers: qcom: Fix leaking of partition name

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Message-ID: <YKxxNY8d/M1fXWr9@yoga>
Date:   Mon, 24 May 2021 22:38:29 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Ansuel Smith <ansuelsmth@...il.com>
Cc:     Andy Gross <agross@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: parsers: qcom: Fix leaking of partition name

On Mon 24 May 19:14 CDT 2021, Ansuel Smith wrote:

> Partition name are already allocated and defined by the ptable struct.
> Skip reallocation of name variable and directly lowercase the name in
> the ptable struct. The name variable was duplicated but never freed.
> The leak was found using kmemleak.
> 

We know that SMEM_AARM_PARTITION_TABLE is accessed by at least the modem
firmware, so I don't think we should change it in place.

I think the appropriate solution is to implement the "cleanup" operation
in struct mtd_part_parser.

Regards,
Bjorn

> Fixes: 803eb124e1a6 ("mtd: parsers: Add Qcom SMEM parser")
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> ---
>  drivers/mtd/parsers/qcomsmempart.c | 22 ++++------------------
>  1 file changed, 4 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/mtd/parsers/qcomsmempart.c b/drivers/mtd/parsers/qcomsmempart.c
> index d9083308f6ba..3d083f0815f8 100644
> --- a/drivers/mtd/parsers/qcomsmempart.c
> +++ b/drivers/mtd/parsers/qcomsmempart.c
> @@ -62,8 +62,8 @@ static int parse_qcomsmem_part(struct mtd_info *mtd,
>  	struct smem_flash_ptable *ptable;
>  	size_t len = SMEM_FLASH_PTABLE_HDR_LEN;
>  	struct mtd_partition *parts;
> -	int ret, i, numparts;
> -	char *name, *c;
> +	int i, numparts;
> +	char *c;
>  
>  	if (IS_ENABLED(CONFIG_MTD_SPI_NOR_USE_4K_SECTORS)
>  			&& mtd->type == MTD_NORFLASH) {
> @@ -125,17 +125,11 @@ static int parse_qcomsmem_part(struct mtd_info *mtd,
>  		if (pentry->name[0] == '\0')
>  			continue;
>  
> -		name = kstrdup(pentry->name, GFP_KERNEL);
> -		if (!name) {
> -			ret = -ENOMEM;
> -			goto out_free_parts;
> -		}
> -
>  		/* Convert name to lower case */
> -		for (c = name; *c != '\0'; c++)
> +		for (c = pentry->name; *c != '\0'; c++)
>  			*c = tolower(*c);
>  
> -		parts[i].name = name;
> +		parts[i].name = pentry->name;
>  		parts[i].offset = le32_to_cpu(pentry->offset) * mtd->erasesize;
>  		parts[i].mask_flags = pentry->attr;
>  		parts[i].size = le32_to_cpu(pentry->length) * mtd->erasesize;
> @@ -149,14 +143,6 @@ static int parse_qcomsmem_part(struct mtd_info *mtd,
>  	*pparts = parts;
>  
>  	return numparts;
> -
> -out_free_parts:
> -	while (--i >= 0)
> -		kfree(parts[i].name);
> -	kfree(parts);
> -	*pparts = NULL;
> -
> -	return ret;
>  }
>  
>  static const struct of_device_id qcomsmem_of_match_table[] = {
> -- 
> 2.31.1
>