On Tue, Sep 03, 2024 at 11:59:43AM +0000, Gui-Dong Han wrote:
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.
Fixes: 4035c72dc1ba ("ice: reconfig host after changing MSI-X on VF") Fixes: 4d38cb44bd32 ("ice: manage VFs MSI-X using resource tracking") Cc: stable@vger.kernel.org Signed-off-by: Gui-Dong Han hanguidong02@outlook.com
v2:
- In this patch v2, an additional resource leak was addressed when
vf->first_vector_idx < 0. The issue is now fixed by adding ice_put_vf(vf) before returning an error. Thanks to Simon Horman for identifying this additional leak scenario.
Thanks for the update,
I agree with the analysis and that the two instances of this problem were introduced by each of the cited commits.
Reviewed-by: Simon Horman horms@kernel.org