linux-kernel - Re: [PATCH] mtd: Add check for kcalloc()

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Message-ID: <87tt9bxwc0.fsf@bootlin.com>
Date: Mon, 03 Feb 2025 09:32:15 +0100
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Jiasheng Jiang <jiashengjiangcool@...il.com>
Cc: richard@....at,  vigneshr@...com,  gmpy.liaowx@...il.com,
  kees@...nel.org,  linux-mtd@...ts.infradead.org,
  linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: Add check for kcalloc()

On 02/02/2025 at 20:54:56 GMT, Jiasheng Jiang <jiashengjiangcool@...il.com> wrote:

> Add a check for kcalloc() and print an error message if it fails.

Checking, yes, but logging, no. IIRC the core does it already if required.

> Fixes: 78c08247b9d3 ("mtd: Support kmsg dumper based on pstore/blk")

Cc: stable is missing

> Signed-off-by: Jiasheng Jiang <jiashengjiangcool@...il.com>
> ---
>  drivers/mtd/mtdpstore.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/mtd/mtdpstore.c b/drivers/mtd/mtdpstore.c
> index 7ac8ac901306..368997155c07 100644
> --- a/drivers/mtd/mtdpstore.c
> +++ b/drivers/mtd/mtdpstore.c
> @@ -423,6 +423,11 @@ static void mtdpstore_notify_add(struct mtd_info *mtd)
>  	longcnt = BITS_TO_LONGS(div_u64(mtd->size, mtd->erasesize));
>  	cxt->badmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
>  
> +	if (!cxt->rmmap || !cxt->usedmap || !cxt->badmap) {
> +		dev_err(&mtd->dev, "failed to allocate memory for map\n");
> +		return;
> +	}
> +
>  	/* just support dmesg right now */
>  	cxt->dev.flags = PSTORE_FLAGS_DMESG;
>  	cxt->dev.zone.read = mtdpstore_read;

What if register_pstore_device() fails? Your only partially fixing the
problem if you don't handle the free()s there as well.

Thanks,
Miquèl