linux-kernel - Re: [PATCH] smackfs: check for allocation failure of kmalloc()

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Message-ID: <88718d10-4435-f5a8-9123-afc73257e0ca@schaufler-ca.com>
Date:   Mon, 13 Jun 2022 07:53:36 -0700
From:   Casey Schaufler <casey@...aufler-ca.com>
To:     Li Qiong <liqiong@...china.com>, James Morris <jmorris@...ei.org>,
        "Serge E . Hallyn" <serge@...lyn.com>
Cc:     linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, yuzhe@...china.com,
        renyu@...china.com, Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH] smackfs: check for allocation failure of kmalloc()

On 6/12/2022 11:22 PM, Li Qiong wrote:
> As the possible failure of the kmalloc(), it should be better
> to check it and print a warning message.

The allocation is done with __GFP_NOFAIL, which assures
it will not fail.

>
> Signed-off-by: Li Qiong <liqiong@...china.com>
> ---
>   security/smack/smackfs.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
> index 4b58526450d4..0d11ba3cb4cd 100644
> --- a/security/smack/smackfs.c
> +++ b/security/smack/smackfs.c
> @@ -695,6 +695,11 @@ static void smk_cipso_doi(void)
>   		       __func__, __LINE__, rc);
>   
>   	doip = kmalloc(sizeof(struct cipso_v4_doi), GFP_KERNEL | __GFP_NOFAIL);
> +	if (unlikely(!doip)) {
> +		printk(KERN_WARNING "%s:%d failed to allocate a memory for doip\n",
> +		       __func__, __LINE__);
> +		return;
> +	}
>   	doip->map.std = NULL;
>   	doip->doi = smk_cipso_doi_value;
>   	doip->type = CIPSO_V4_MAP_PASS;