CVE-2025-39979

Technical Description

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

net/mlx5: fs, fix UAF in flow counter release

Fix a kernel trace [1] caused by releasing an HWS action of a local flow

counter in mlx5_cmd_hws_delete_fte(), where the HWS action refcount and

mutex were not initialized and the counter struct could already be freed

when deleting the rule.

Fix it by adding the missing initializations and adding refcount for the

local flow counter struct.

[1] Kernel log:

Call Trace:

<TASK>

dump_stack_lvl+0x34/0x48

mlx5_fs_put_hws_action.part.0.cold+0x21/0x94 [mlx5_core]

mlx5_fc_put_hws_action+0x96/0xad [mlx5_core]

mlx5_fs_destroy_fs_actions+0x8b/0x152 [mlx5_core]

mlx5_cmd_hws_delete_fte+0x5a/0xa0 [mlx5_core]

del_hw_fte+0x1ce/0x260 [mlx5_core]

mlx5_del_flow_rules+0x12d/0x240 [mlx5_core]

? ttwu_queue_wakelist+0xf4/0x110

mlx5_ib_destroy_flow+0x103/0x1b0 [mlx5_ib]

uverbs_free_flow+0x20/0x50 [ib_uverbs]

destroy_hw_idr_uobject+0x1b/0x50 [ib_uverbs]

uverbs_destroy_u

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References