GHSA-HJXX-JPR5-HFGW
Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 12:31In 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": [],
"aliases": [
"CVE-2026-98014"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-25T11:17:29Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5: E-Switch, prevent mc_list repopulation during vport disable\n\nIn mlx5_esw_vport_disable(), move esw_apply_vport_rx_mode() ahead\nof esw_vport_change_handle_locked() so vport-\u003eallmulti_rule is\nNULL before the change handler observes it.\n\nDuring FW-fatal recovery the disable runs while dev-\u003estate ==\nINTERNAL_ERROR. The promisc query inside esw_update_vport_rx_mode()\nfails and returns early, leaving vport-\u003eallmulti_rule intact, so\nesw_update_vport_mc_promisc() runs and adds MLX5_ACTION_ADD entries\nto vport-\u003emc_list whose flow rules are then installed in the FDB\nby esw_add_mc_addr(). esw_destroy_legacy_table() tears down the\nFDB with those refs still held, corrupting the sub-tree and\nleaving dangling flow_rule pointers in vport-\u003emc_list.\n\nTwo-stage failure on `echo 1 \u003e /sys/bus/pci/devices/\u003cbdf\u003e/reset`:\n\n refcount_t: underflow; use-after-free.\n tree_put_node+0xef/0x110 [mlx5_core]\n clean_tree+0x44/0xd0 [mlx5_core] (x5)\n mlx5_fs_core_cleanup+0x57/0x1c0 [mlx5_core]\n mlx5_unload+0x65/0xd0 [mlx5_core]\n ... mlx5_health_try_recover\n\n BUG: unable to handle page fault for address: 0000000003000055\n down_write+0x1c/0x60\n mlx5_del_flow_rules+0x33/0x1f0 [mlx5_core]\n esw_del_mc_addr+0x7b/0x170 [mlx5_core]\n esw_apply_vport_addr_list+0x56/0xf0 [mlx5_core]\n esw_vport_change_handle_locked+0x28b/0x310 [mlx5_core]\n mlx5_esw_vport_enable+0x270/0x4a0 [mlx5_core]\n ... mlx5_load ... mlx5_health_try_recover\n\nesw_apply_vport_rx_mode(false, false) clears vport-\u003eallmulti_rule\nvia its local state machine even when the FW del fails. With the\nrule NULL the !IS_ERR_OR_NULL(allmulti_rule) gate in the change\nhandler closes, no rules are installed during disable, and the\nreload starts with a clean mc_list.",
"id": "GHSA-hjxx-jpr5-hfgw",
"modified": "2026-09-25T12:31:33Z",
"published": "2026-09-25T12:31:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98014"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/668e050429c7ca688cf4e7112f97f0cd269d446b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/69904608e25e8ba58111aadd9210892cf3876201"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/72cfcb79026cffb6490f5044153a841d360b0cfc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c0c6f4ba8a37688f7b4d4044898d88f0450d44c2"
}
],
"schema_version": "1.4.0",
"severity": []
}
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