On Tue, Apr 06, 2021 at 06:53:32PM -0500, Aditya Pakki wrote:
> In virtio_fs_get_tree, after fm is freed, it is again freed in case
> s_root is NULL and virtio_fs_fill_super() returns an error. To avoid
> a double free, set fm to NULL.
>
> Signed-off-by: Aditya Pakki <pakki...@umn.edu>
> ---
> fs/fuse/virtio_fs.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
> index 4ee6f734ba83..a7484c1539bf 100644
> --- a/fs/fuse/virtio_fs.c
> +++ b/fs/fuse/virtio_fs.c
> @@ -1447,6 +1447,7 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
> if (fsc->s_fs_info) {
> fuse_conn_put(fc);
> kfree(fm);
> + fm = NULL;
I think both the code paths are mutually exclusive and that's why we
don't double free it.
sget_fc(), can either return existing super block which is already
initialized, or it can create a new super block which need to
initialize further.
If if get an existing super block, in that case fs->s_fs_info will
still be set and we need to free fm (as we did not use it). But in
that case this super block is already initialized so sb->s_root
should be non-null and we will not call virtio_fs_fill_super()
on this. And hence we will not get into kfree(fm) again.
Same applies to fuse_conn_put(fc) call as well.
So I think this patch is not needed. I think sget_fc() semantics are
not obvious and that confuses the reader of the code.
Thanks
Vivek
> }
> if (IS_ERR(sb))
> return PTR_ERR(sb);
> --
> 2.25.1
>
