Re: [PATCH linux 2/2] net sched actions: fix refcount decrement on error

From: Roman Mashak <mrv@mojatatu.com>
To: Wolfgang Bumiller <w.bumiller@proxmox.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH linux 2/2] net sched actions: fix refcount decrement on error
Date: Thu, 13 Apr 2017 09:39:43 -0400	[thread overview]
Message-ID: <85inm8pgtc.fsf@mojatatu.com> (raw)
In-Reply-To: <20170412142140.26649-3-w.bumiller@proxmox.com> (Wolfgang Bumiller's message of "Wed, 12 Apr 2017 16:21:40 +0200")

Wolfgang Bumiller <w.bumiller@proxmox.com> writes:

> If memory allocation for nla_memdup_cookie() fails
> module_put has to be guarded by the same condition as it was
> before the TCA_ACT_COOKIE has been added as stated in the
> comment afterwards:
>

What if a new entry has been created, and a_o->init returns
ACT_P_CREATED, but cookie allocation fails, do we not remove module
reference count?

[...]

>  		if (cklen > TC_COOKIE_MAX_SIZE) {
> -			err = -EINVAL;
>  			tcf_hash_release(a, bind);
> -			goto err_mod;
> +			if (err != ACT_P_CREATED)
> +				module_put(a_o->owner);
> +			err = -EINVAL;
> +			goto err_out;
>  		}
>  
>  		if (nla_memdup_cookie(a, tb) < 0) {
> -			err = -ENOMEM;
>  			tcf_hash_release(a, bind);
> -			goto err_mod;
> +			if (err != ACT_P_CREATED)
> +				module_put(a_o->owner);
> +			err = -ENOMEM;
> +			goto err_out;
>  		}
>  	}