Re: [PATCH] nfs: fix memory leak in nfs_get_sb with CONFIG_NFS_V4

[Xiaotian Feng]

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@xxxxxxxxxx>
> > Cc: Trond Myklebust<Trond.Myklebust@xxxxxxxxxx>
> > Cc: Chuck Lever<chuck.lever@xxxxxxxxxx>
> > Cc: Benny Halevy<bhalevy@xxxxxxxxxxx>
> > Cc: Al Viro<viro@xxxxxxxxxxxxxxxxxx>
> > Cc: Andy Adamson<andros@xxxxxxxxxx>
> > ---
> >   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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