CVE-2026-98014net/mlx5: E-Switch, prevent mc_list repopulation during vport disable

Official description

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: E-Switch, prevent mc_list repopulation during vport disable In mlx5_esw_vport_disable(), move esw_apply_vport_rx_mode() ahead of esw_vport_change_handle_locked() so vport->allmulti_rule is NULL before the change handler observes it. During FW-fatal recovery the disable runs while dev->state == INTERNAL_ERROR. The promisc query inside esw_update_vport_rx_mode() fails and returns early, leaving vport->allmulti_rule intact, so esw_update_vport_mc_promisc() runs and adds MLX5_ACTION_ADD entries to vport->mc_list whose flow rules are then installed in the FDB by esw_add_mc_addr(). esw_destroy_legacy_table() tears down the FDB with those refs still held, corrupting the sub-tree and leaving dangling flow_rule pointers in vport->mc_list. Two-stage failure on `echo 1 > /sys/bus/pci/devices/<bdf>/reset`: refcount_t: underflow; use-after-free. tree_put_node+0xef/0x110 [mlx5_core] clean_tree+0x44/0xd0 [mlx5_core] (x5) mlx5_fs_core_cleanup+0x57/0x1c0 [mlx5_core] mlx5_unload+0x65/0xd0 [mlx5_core] ... mlx5_health_try_recover BUG: unable to handle page fault for address: 0000000003000055 down_write+0x1c/0x60 mlx5_del_flow_rules+0x33/0x1f0 [mlx5_core] esw_del_mc_addr+0x7b/0x170 [mlx5_core] esw_apply_vport_addr_list+0x56/0xf0 [mlx5_core] esw_vport_change_handle_locked+0x28b/0x310 [mlx5_core] mlx5_esw_vport_enable+0x270/0x4a0 [mlx5_core] ... mlx5_load ... mlx5_health_try_recover esw_apply_vport_rx_mode(false, false) clears vport->allmulti_rule via its local state machine even when the FW del fails. With the rule NULL the !IS_ERR_OR_NULL(allmulti_rule) gate in the change handler closes, no rules are installed during disable, and the reload starts with a clean mc_list.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/413e04adcc1fd263cf02b1b83b4a0dbdc66bcee9
• https://git.kernel.org/stable/c/2196f9d3358b00fcb28835a5fde14071f51ecb96
• https://git.kernel.org/stable/c/5a2b87dfceccf9065157a14a599d395c2b6281b8
• https://git.kernel.org/stable/c/69904608e25e8ba58111aadd9210892cf3876201
• https://git.kernel.org/stable/c/72cfcb79026cffb6490f5044153a841d360b0cfc
• https://git.kernel.org/stable/c/668e050429c7ca688cf4e7112f97f0cd269d446b
• https://git.kernel.org/stable/c/c0c6f4ba8a37688f7b4d4044898d88f0450d44c2