linux-kernel - Re: [PATCH] nfs: fix memory leak in nfs_get_sb with CONFIG_NFS

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Date:	Fri, 23 Apr 2010 10:29:23 +0800
From:	Xiaotian Feng <dfeng@...hat.com>
To:	Chuck Lever <chuck.lever@...cle.com>
CC:	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
	Trond Myklebust <Trond.Myklebust@...app.com>,
	Benny Halevy <bhalevy@...asas.com>,
	Al Viro <viro@...IV.linux.org.uk>,
	Andy Adamson <andros@...app.com>
Subject: Re: [PATCH] nfs: fix memory leak in nfs_get_sb with CONFIG_NFS_V4

On 04/23/2010 12:09 AM, Chuck Lever wrote:
> 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@...hat.com>
>> Cc: Trond Myklebust<Trond.Myklebust@...app.com>
>> Cc: Chuck Lever<chuck.lever@...cle.com>
>> Cc: Benny Halevy<bhalevy@...asas.com>
>> Cc: Al Viro<viro@...IV.linux.org.uk>
>> Cc: Andy Adamson<andros@...app.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?

I don't think we need to free data->nfs_server.hostname and 
data->fscache_uniq, they were freed in the out label ;-)
>
>>           goto out;
>>       }

out:
         kfree(data->nfs_server.hostname);
         kfree(data->mount_server.hostname);
         kfree(data->fscache_uniq);
         security_free_mnt_opts(&data->lsm_opts);
>>   #endif    /* CONFIG_NFS_V4 */
>
>

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