linux-kernel - Re: [PATCH] afs: Fix afs_cb_interest refcnt leak in afs_select

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Message-ID: <3193793.1590509939@warthog.procyon.org.uk>
Date:   Tue, 26 May 2020 17:18:59 +0100
From:   David Howells <dhowells@...hat.com>
To:     Xiyu Yang <xiyuyang19@...an.edu.cn>
Cc:     dhowells@...hat.com, linux-afs@...ts.infradead.org,
        linux-kernel@...r.kernel.org, yuanxzhang@...an.edu.cn,
        kjlu@....edu, Xin Tan <tanxin.ctf@...il.com>
Subject: Re: [PATCH] afs: Fix afs_cb_interest refcnt leak in afs_select_fileserver()

Xiyu Yang <xiyuyang19@...an.edu.cn> wrote:

>  	error = afs_wait_for_fs_probes(fc->server_list, fc->untried);
> -	if (error < 0)
> +	if (error < 0) {
> +		afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
>  		goto failed_set_error;
> +	}

Ummm...  Did you try this?  afs_end_vnode_operation() should then cause a
double free because you don't clear fc->cbi.

You can try it by installing the kafs-client package if your distribution has
it available and starting the afs.mount service or doing:

	mount -t afs none /afs -o dyn

and then:

	ls /afs/grand.central.org/

David