linux-kernel - Re: [PATCH] crypto: ccp - fix memleak in ccp_init_dm

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Message-ID: <3f033585-91c6-1d70-be1e-f083fc855aed@amd.com>
Date:   Sat, 25 Nov 2023 09:10:09 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Dinghao Liu <dinghao.liu@....edu.cn>
Cc:     John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] crypto: ccp - fix memleak in ccp_init_dm_workarea

On 11/23/23 01:03, Dinghao Liu wrote:
> When dma_map_single() fails, we should free wa->address to
> prevent potential memleak.

You should expand on this a bit more. The ccp_dm_free() function is 
normally called to free that memory, but many of the call spots don't 
expect to have to call ccp_dm_free() on an error return from 
ccp_init_dm_workarea(). Because of that, the memory is freed in 
ccp_init_dm_workarea().

So a more detailed commit message about why this change is needed should 
be provided.

> 
> Fixes: 63b945091a07 ("crypto: ccp - CCP device driver and interface support")
> Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
> ---
>   drivers/crypto/ccp/ccp-ops.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
> index aa4e1a500691..45552ae6347e 100644
> --- a/drivers/crypto/ccp/ccp-ops.c
> +++ b/drivers/crypto/ccp/ccp-ops.c
> @@ -179,8 +179,10 @@ static int ccp_init_dm_workarea(struct ccp_dm_workarea *wa,
>   
>   		wa->dma.address = dma_map_single(wa->dev, wa->address, len,
>   						 dir);
> -		if (dma_mapping_error(wa->dev, wa->dma.address))
> +		if (dma_mapping_error(wa->dev, wa->dma.address)) {
> +			kfree(wa->address);

If future changes should result in ccp_dm_free() being called on an error 
returned from ccp_init_dm_workarea(), you should add:

			wa->address = NULL;

Thanks,
Tom

>   			return -ENOMEM;
> +		}
>   
>   		wa->dma.length = len;
>   	}