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

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Message-ID: <CANeGvZWi3rZoLcgAyTVU_nKTaE0pHxPYzdqZy2oBsmH+LpUryg@mail.gmail.com>
Date: Mon, 3 Feb 2025 21:34:38 -0500
From: Jiasheng Jiang <jiashengjiangcool@...il.com>
To: Miquel Raynal <miquel.raynal@...tlin.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()

Hi Miquel,

On Mon, Feb 3, 2025 at 3:32 AM Miquel Raynal <miquel.raynal@...tlin.com> wrote:
>
> 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

Thanks, I have submitted a v2 to fix the problems above.

-Jiasheng