linux-kernel - Re: [PATCH] IB/rxe: check for allocation failure on elem

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Date:   Sat, 9 Sep 2017 15:56:07 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Colin King <colin.king@...onical.com>
Cc:     Moni Shoua <monis@...lanox.com>,
        Doug Ledford <dledford@...hat.com>,
        Sean Hefty <sean.hefty@...el.com>,
        Hal Rosenstock <hal.rosenstock@...il.com>,
        linux-rdma@...r.kernel.org, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] IB/rxe: check for allocation failure on elem

On Fri, Sep 08, 2017 at 03:37:45PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
>
> The allocation for elem may fail (especially because we're using
> GFP_ATOMIC) so best to check for a null return.  This fixes a potential
> null pointer dereference when assigning elem->pool.
>
> Detected by CoverityScan CID#1357507 ("Dereference null return value")
>
> Fixes: 8700e3e7c485 ("Soft RoCE driver")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/infiniband/sw/rxe/rxe_pool.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c
> index c1b5f38f31a5..3b4916680018 100644
> --- a/drivers/infiniband/sw/rxe/rxe_pool.c
> +++ b/drivers/infiniband/sw/rxe/rxe_pool.c
> @@ -404,6 +404,8 @@ void *rxe_alloc(struct rxe_pool *pool)
>  	elem = kmem_cache_zalloc(pool_cache(pool),
>  				 (pool->flags & RXE_POOL_ATOMIC) ?
>  				 GFP_ATOMIC : GFP_KERNEL);
> +	if (!elem)
> +		return NULL;
>

It is not enough to simply return NULL, you also should release "pool" too.

Thanks

>  	elem->pool = pool;
>  	kref_init(&elem->ref_cnt);
> --
> 2.14.1
>

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