Bug 2516566 (CVE-2026-72307)

Summary: CVE-2026-72307 kernel: mlxsw: fix refcount leak in mlxsw_sp_vrs_lpm_tree_replace()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's `mlxsw` driver. When the `mlxsw_sp_vrs_lpm_tree_replace()` function encounters an error during Virtual Router (VR) replacement operations, its rollback mechanism fails to correctly release resources. This leads to a reference count leak, where system resources are not properly deallocated. Over time, this resource exhaustion could potentially result in a denial of service (DoS) condition, making the system unresponsive.
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Description OSIDB Bzimport 2026-08-15 06:19:17 UTC
In the Linux kernel, the following vulnerability has been resolved:

mlxsw: fix refcount leak in mlxsw_sp_vrs_lpm_tree_replace()

When mlxsw_sp_vrs_lpm_tree_replace() fails after replacing some VRs,
the error rollback loop does not correctly revert the preceding
replacements. The loop decrements the index but fails to update the
vr pointer, which still points to the VR that caused the failure. As
a result, the condition and the rollback call always operate on the
same VR, potentially calling mlxsw_sp_vr_lpm_tree_replace() multiple
times on it while never rolling back the earlier VRs. Those VRs
continue to hold a reference to new_tree acquired via
mlxsw_sp_lpm_tree_hold(), leaking the reference count of new_tree.

Fix by reinitializing vr inside the error loop with the updated index:

	vr = &mlxsw_sp->router->vrs[i];

so that the loop correctly iterates over all VRs that were actually
replaced.