From: Chuck Lever <chuck.lever@oracle.com>
Subject: Re: [PATCH] nfs: fix memory leak in nfs_get_sb with CONFIG_NFS_V4
Date: Thu, 22 Apr 2010 12:09:54 -0400
Message-ID: <4BD074D2.8070300@oracle.com>
References: <1271933777-26244-1-git-send-email-dfeng@redhat.com>
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Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org,
	Trond Myklebust <Trond.Myklebust@netapp.com>,
	Benny Halevy <bhalevy@panasas.com>,
	Al Viro <viro@ZenIV.linux.org.uk>,
	Andy Adamson <andros@netapp.com>
To: Xiaotian Feng <dfeng@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1271933777-26244-1-git-send-email-dfeng@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-nfs.vger.kernel.org>

On 04/22/2010 06:56 AM, Xiaotian Feng wrote:
> With CONFIG_NFS_V4 and data version 4, nfs_get_sb will allocate memory for
> export_path in nfs4_validate_text_mount_data, so we need to free it then.
> This is addressed in following kmemleak report:
>
> unreferenced object 0xffff88016bf48a50 (size 16):
>    comm "mount.nfs", pid 22567, jiffies 4651574704 (age 175471.200s)
>    hex dump (first 16 bytes):
>      2f 6f 70 74 2f 77 6f 72 6b 00 6b 6b 6b 6b 6b a5  /opt/work.kkkkk.
>    backtrace:
>      [<ffffffff814b34f9>] kmemleak_alloc+0x60/0xa7
>      [<ffffffff81102c76>] kmemleak_alloc_recursive.clone.5+0x1b/0x1d
>      [<ffffffff811046b3>] __kmalloc_track_caller+0x18f/0x1b7
>      [<ffffffff810e1b08>] kstrndup+0x37/0x54
>      [<ffffffffa0336971>] nfs_parse_devname+0x152/0x204 [nfs]
>      [<ffffffffa0336af3>] nfs4_validate_text_mount_data+0xd0/0xdc [nfs]
>      [<ffffffffa0338deb>] nfs_get_sb+0x325/0x736 [nfs]
>      [<ffffffff81113671>] vfs_kern_mount+0xbd/0x17c
>      [<ffffffff81113798>] do_kern_mount+0x4d/0xed
>      [<ffffffff81129a87>] do_mount+0x787/0x7fe
>      [<ffffffff81129b86>] sys_mount+0x88/0xc2
>      [<ffffffff81009b42>] system_call_fastpath+0x16/0x1b
>
> Signed-off-by: Xiaotian Feng<dfeng@redhat.com>
> Cc: Trond Myklebust<Trond.Myklebust@netapp.com>
> Cc: Chuck Lever<chuck.lever@oracle.com>
> Cc: Benny Halevy<bhalevy@panasas.com>
> Cc: Al Viro<viro@ZenIV.linux.org.uk>
> Cc: Andy Adamson<andros@netapp.com>
> ---
>   fs/nfs/super.c |    1 +
>   1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index e016372..44e6567 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -2187,6 +2187,7 @@ static int nfs_get_sb(struct file_system_type *fs_type,
>   	if (data->version == 4) {
>   		error = nfs4_try_mount(flags, dev_name, data, mnt);
>   		kfree(data->client_address);
> +		kfree(data->nfs_server.export_path);

nfs4_try_mount's other call site in fs/nfs/super.c also frees 
data->nfs_server.hostname and data->fscache_uniq.  Does that need to 
happen here too?

>   		goto out;
>   	}
>   #endif	/* CONFIG_NFS_V4 */


-- 
chuck[dot]lever[at]oracle[dot]com