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.
Published: 2026-09-25
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Fri, 25 Sep 2026 18:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Fri, 25 Sep 2026 10:30:00 +0000

Type Values Removed Values Added
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.
Title net/mlx5: E-Switch, prevent mc_list repopulation during vport disable
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-09-25T10:23:37.131Z

Reserved: 2026-09-25T10:19:56.069Z

Link: CVE-2026-98014

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-25T11:17:29.767

Modified: 2026-09-25T11:17:29.767

Link: CVE-2026-98014

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-25T17:45:17Z

Weaknesses