Re: [Qemu-devel] [PATCH] 9pfs: fix information leak in xattr read

[Li Qiang]

Yes, allocation here is also causing a memory leak issue.
I will try to look more at it.

On 2016-09-28 16:47 GMT+08:00 Greg Kurz <address@hidden> wrote:
>
>
> Heh not exactly... I'm just wondering why we allocate
> xattr_fidp->fs.xattr.value
> here if we don't use it. Can you please investigate if it is possible to
> defer
> allocation until it is really needed ?
>
> Thanks.
>
> --
> Greg
>
> > 2016-09-27 12:44 GMT+08:00 Li Qiang <address@hidden>:
> >
> > > From: Li Qiang <address@hidden>
> > >
> > > 9pfs uses g_malloc() to allocate the xattr memory space, if the guest
> > > reads this memory before writing to it, this will leak host heap
> > > memory to the guest. This patch avoid this.
> > >
> > > Signed-off-by: Li Qiang <address@hidden>
> > > ---
> > >  hw/9pfs/9p.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> > > index b1ff8e7..4db1bd8 100644
> > > --- a/hw/9pfs/9p.c
> > > +++ b/hw/9pfs/9p.c
> > > @@ -3291,7 +3291,7 @@ static void v9fs_xattrcreate(void *opaque)
> > >      xattr_fidp->fs.xattr.flags = flags;
> > >      v9fs_string_init(&xattr_fidp->fs.xattr.name);
> > >      v9fs_string_copy(&xattr_fidp->fs.xattr.name, &name);
> > > -    xattr_fidp->fs.xattr.value = g_malloc(size);
> > > +    xattr_fidp->fs.xattr.value = g_malloc0(size);
> > >      err = offset;
> > >      put_fid(pdu, file_fidp);
> > >  out_nofid:
> > > --
> > > 1.8.3.1
> > >
> > >
>
>