linux-kernel - Re: [PATCH] crypto: octeontx2: fix potential null pointer access

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Message-ID: <20220527081928.GO2168@kadam>
Date:   Fri, 27 May 2022 11:19:28 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Shijith Thotton <sthotton@...vell.com>
Cc:     Arnaud Ebalard <arno@...isbad.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Boris Brezillon <bbrezillon@...nel.org>,
        linux-crypto@...r.kernel.org, jerinj@...vell.com,
        sgoutham@...vell.com, Srujana Challa <schalla@...vell.com>,
        "David S. Miller" <davem@...emloft.net>,
        Harman Kalra <hkalra@...vell.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        Kees Cook <keescook@...omium.org>,
        Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] crypto: octeontx2: fix potential null pointer access

On Fri, May 27, 2022 at 01:27:56PM +0530, Shijith Thotton wrote:
> Added missing checks to avoid null pointer dereference.
> 
> The patch fixes below issues reported by klocwork tool:

Don't fix false positives to make a tool happy.  Fix the tool.  (Unless
the patch makes the code simpler, then it's fine).

> 1. Pointer 'pcim_iomap_table(pdev)' returned from call to function
>    'pcim_iomap_table' at line 365 may be NULL and will be dereferenced
>    at line 365 in otx2_cptvf_main.c. Also there is a similar error on
>    line 734 in otx2_cptpf_main.c.
> 2. Pointer 'strsep( &val, ":" )' returned from call to function 'strsep'
>    at line 1608 may be NULL and will be dereferenced at line 1608. Also
>    there are 2 similar errors on lines 1620, 1632 in otx2_cptpf_ucode.c.
> 
> Signed-off-by: Shijith Thotton <sthotton@...vell.com>
> ---
>  .../crypto/marvell/octeontx2/otx2_cptpf_main.c |  9 ++++++++-
>  .../marvell/octeontx2/otx2_cptpf_ucode.c       | 18 +++++++++++++++---
>  .../crypto/marvell/octeontx2/otx2_cptvf_main.c |  9 ++++++++-
>  3 files changed, 31 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/crypto/marvell/octeontx2/otx2_cptpf_main.c b/drivers/crypto/marvell/octeontx2/otx2_cptpf_main.c
> index a402ccfac557..ae57cee424f0 100644
> --- a/drivers/crypto/marvell/octeontx2/otx2_cptpf_main.c
> +++ b/drivers/crypto/marvell/octeontx2/otx2_cptpf_main.c
> @@ -703,6 +703,7 @@ static int otx2_cptpf_probe(struct pci_dev *pdev,
>  {
>  	struct device *dev = &pdev->dev;
>  	struct otx2_cptpf_dev *cptpf;
> +	void __iomem * const *iomap;
>  	int err;
>  
>  	cptpf = devm_kzalloc(dev, sizeof(*cptpf), GFP_KERNEL);
> @@ -731,7 +732,13 @@ static int otx2_cptpf_probe(struct pci_dev *pdev,
>  	pci_set_drvdata(pdev, cptpf);
>  	cptpf->pdev = pdev;
>  
> -	cptpf->reg_base = pcim_iomap_table(pdev)[PCI_PF_REG_BAR_NUM];
> +	iomap = pcim_iomap_table(pdev);

I don't know if a check is required here or not...  The comments to
pcim_iomap_table() say it is, "guaranteed to succeed once  allocated."

> +	if (!iomap) {
> +		dev_err(dev, "Failed to get iomap table\n");
> +		err = -ENODEV;
> +		goto clear_drvdata;
> +	}
> +	cptpf->reg_base = iomap[PCI_PF_REG_BAR_NUM];
>  
>  	/* Check if AF driver is up, otherwise defer probe */
>  	err = cpt_is_pf_usable(cptpf);
> diff --git a/drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c b/drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c
> index 9cba2f714c7e..b91401929fc6 100644
> --- a/drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c
> +++ b/drivers/crypto/marvell/octeontx2/otx2_cptpf_ucode.c
> @@ -1605,7 +1605,11 @@ int otx2_cpt_dl_custom_egrp_create(struct otx2_cptpf_dev *cptpf,
>  		if (!strncasecmp(val, "se", 2) && strchr(val, ':')) {
                                                  ^^^^^^^^^^^^^^^^
We know it can't be NULL.

>  			if (has_se || ucode_idx)
>  				goto err_print;
> -			tmp = strim(strsep(&val, ":"));
> +			tmp = strsep(&val, ":");
> +			if (tmp != NULL)
> +				tmp = strim(tmp);
> +			else
> +				goto err_print;
>  			if (!val)
>  				goto err_print;
>  			if (strlen(tmp) != 2)

The rest is all the same.  Likely or definitely false positives.

regards,
dan carpenter