Re: [PATCH] nvme-fc: fix double free of fabrics options when nvme_add_ctrl() fails

[Niklas Cassel <cassel@kernel.org>]

Hello Keith,

On Wed, Aug 19, 2026 at 09:28:08AM -0600, Keith Busch wrote:
> On Mon, Aug 17, 2026 at 05:10:23PM +0200, Niklas Cassel wrote:
> > It seems like Keith did prefer your patch, but as you said, your patch does
> > not avoid a NULL pointer dereference in nvme_auth_free().
> 
> But you're replacing a NULL pointer dereference to a derefence to freed
> memory. That should be fixed too, and I'm just saying checking a pointer
> for NULL before dereferencing it is more clear than checking if a list
> is empty.

I am not following.

The options is freed in two different places, depending on if the
ops->create_ctrl(dev, opts) call in fabrics.c:nvmf_create_ctrl() was
successful or not.

If the ops->create_ctrl(dev, opts) call in fabrics.c:nvmf_create_ctrl() was
successful, the teardown path will be:
core.c:nvme_free_ctrl(), which calls nvme_auth_free() (which will use
the options), nvme_free_ctrl() will then call ctrl->ops->free_ctrl(ctrl)
which will free the options (since the ops->create_ctrl() call was successful,
the ctrl will be on the linked-list).

If the ops->create_ctrl(dev, opts) call in fabrics.c:nvmf_create_ctrl()
fails, the teardown path will be:
core.c:nvme_free_ctrl(), which calls nvme_auth_free() (which will use
the options), nvme_free_ctrl() will then call ctrl->ops->free_ctrl(ctrl)
which will not free the options (since the ops->create_ctrl() call failed,
the ctrl will not be on the linked-list), fabrics.c:nvmf_create_ctrl() will
thus goto out_module_put, which then does a goto out_free_opts, which
calls nvmf_free_options().

In both cases, nvme_auth_free() will access memory that has not yet been
freed. So I don't see us dereferencing freed memory.


Kind regards,
Niklas