linux-kernel - Re: [PATCH] nfsd: fix memory leak of async

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Date:   Tue, 17 Jul 2018 12:30:05 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Colin King <colin.king@...onical.com>
Cc:     "J . Bruce Fields" <bfields@...ldses.org>,
        Jeff Layton <jlayton@...nel.org>, linux-nfs@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfsd: fix memory leak of async_copy

On Mon, Jul 16, 2018 at 01:09:54PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> In the case where async_copy is successfully allocated but
> the call to nfs4_init_cp_state fails, async_copy is not
> currently freed and the memory is leaked. Fix this by kfree'ing
> it before returning.
> 
> Detected by CoverityScan, CID#1471823 ("Resource leak")
> 
> Fixes: beb1814d5a8a ("NFSD create new stateid for async copy")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  fs/nfsd/nfs4proc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 8f3368353aaf..3fb96a2708b9 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1295,8 +1295,10 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>  		async_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
>  		if (!async_copy)
>  			goto out;
> -		if (!nfs4_init_cp_state(nn, copy))
> +		if (!nfs4_init_cp_state(nn, copy)) {
> +			kfree(async_copy);
>  			goto out;

It really feels like both this and the kzalloc() failure should be doing
an of fput() of copy->file_src and copy->file_dst.  The goto out_err
does an list_del(&copy->copies); but it happens before the
"list_add(&async_copy->copies ..." so that's likely wrong as well.

regards,
dan carpenter