netdev - Re: [PATCH net-next] rds: do not call ->conn_alloc with GFP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180213.120421.840213231623736121.davem@davemloft.net>
Date:   Tue, 13 Feb 2018 12:04:21 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     sowmini.varadhan@...cle.com
Cc:     netdev@...r.kernel.org, santosh.shilimkar@...cle.com,
        rds-devel@....oracle.com
Subject: Re: [PATCH net-next] rds: do not call ->conn_alloc with GFP_KERNEL

From: Sowmini Varadhan <sowmini.varadhan@...cle.com>
Date: Mon, 12 Feb 2018 15:30:38 -0800

> diff --git a/net/rds/connection.c b/net/rds/connection.c
> index 94e190f..d0f5889 100644
> --- a/net/rds/connection.c
> +++ b/net/rds/connection.c
> @@ -221,6 +221,8 @@ static void __rds_conn_path_init(struct rds_connection *conn,
>  		conn->c_path[i].cp_index = i;
>  	}
>  	rcu_read_lock();
> +	gfp &= ~GFP_KERNEL;
> +	gfp |= GFP_ATOMIC;
>  	if (rds_destroy_pending(conn))
>  		ret = -ENETDOWN;
>  	else

I'd never seen this kind of gfp masking before, so I did a grep around
and the only cases I saw of this kind of usage were for things like
GFP_DMA and such.

I could not find one case that did it to convert a sleeping into a non-
sleeping GFP mask.

Let's not over-engineer this.  For one thing, whatever allocation bits
came down from the callers, we are going to lose here.

So just pass straight GFP_ATOMIC into the routines below here instead
of the 'gfp' variable.

Thanks.