linux-kernel - Re: [PATCH] drivers: mtd: Fix potential memory leak in mtd_check_of

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Date:   Thu, 22 Jun 2023 23:02:17 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Yang Rong <yangrong@...o.com>
Cc:     Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-mtd@...ts.infradead.org (open list:MEMORY TECHNOLOGY DEVICES
        (MTD)), linux-kernel@...r.kernel.org (open list),
        opensource.kernel@...o.com, luhongfei@...o.com
Subject: Re: [PATCH] drivers: mtd: Fix potential memory leak in
 mtd_check_of_node

Hello,

yangrong@...o.com wrote on Wed, 21 Jun 2023 10:43:22 +0800:

> The for_each_child_of_node API internally increases the reference count
> for each child node traversed. If a break statement is encountered inside
> the loop, it leaves one reference unbalanced leading to a memory leak.
> 
> The function mtd_check_of_node in drivers/mtd/mtdcore.c uses such a loop
> and a break statement without a corresponding of_node_put.
> 
> This patch fixes the potential memory leak by adding a call to
> of_node_put before the break statement inside the for_each_child_of_node
> loop in the function mtd_check_of_node.

I wanted to take this patch but it failed to apply cleanly. Please now
wait for -rc1 and send an updated v2.
 
> 
> Signed-off-by: Yang Rong <yangrong@...o.com>
> ---
>  drivers/mtd/mtdcore.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
> index e00b12aa5ec9..b02cb8b1a38d 100644
> --- a/drivers/mtd/mtdcore.c
> +++ b/drivers/mtd/mtdcore.c
> @@ -591,6 +591,7 @@ static void mtd_check_of_node(struct mtd_info *mtd)
>                 if (plen == mtd_name_len &&
>                     !strncmp(mtd->name, pname + offset, plen)) {
>                         mtd_set_of_node(mtd, mtd_dn);
> +                       of_node_put(mtd_dn);
>                         break;
>                 }
>         }
> --
> 2.35.3
> 
> 
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> Thank you


Thanks,
Miquèl