ice: Fix improper handling of refcount in ice_sriov_set_msix_vec_count()

In the Linux kernel, the following vulnerability has been resolved:

ice: Fix improper handling of refcount in ice_sriov_set_msix_vec_count()

This patch addresses an issue with improper reference count handling in the

ice_sriov_set_msix_vec_count() function.

First, the function calls ice_get_vf_by_id(), which increments the

reference count of the vf pointer. If the subsequent call to

ice_get_vf_vsi() fails, the function currently returns an error without

decrementing the reference count of the vf pointer, leading to a reference

count leak. The correct behavior, as implemented in this patch, is to

decrement the reference count using ice_put_vf(vf) before returning an

error when vsi is NULL.

Second, the function calls ice_sriov_get_irqs(), which sets

vf->first_vector_idx. If this call returns a negative value, indicating an

error, the function returns an error without decrementing the reference

count of the vf pointer, resulting in another reference count leak. The

patch addresses this by adding a call to ice_put_vf(vf) before returning

an error when vf->first_vector_idx < 0.

This bug was identified by an experimental static analysis tool developed

by our team. The tool specializes in analyzing reference count operations

and identifying potential mismanagement of reference counts. In this case,

the tool flagged the missing decrement operation as a potential issue,

leading to this patch.