CVE-2023-54148 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Move representor neigh cleanup to profile cleanup_tx
For IP tunnel encapsulation in ECMP (Equal-Cost Multipath) mode, as the flow is duplicated to the peer eswitch, the related neighbour information on the peer uplink representor is created as well.
In the cited commit, eswitch devcom unpair is moved to uplink unload API, specifically the profile->cleanup_tx. If there is a encap rule offloaded in ECMP mode, when one eswitch does unpair (because of unloading the driver, for instance), and the peer rule from the peer eswitch is going to be deleted, the use-after-free error is triggered while accessing neigh info, as it is already cleaned up in uplink's profile->disable, which is before its profile->cleanup_tx.
To fix this issue, move the neigh cleanup to profile's cleanup_tx callback, and after mlx5e_cleanup_uplink_rep_tx is called. The neigh init is moved to init_tx for symmeter.
[ 2453.376299] BUG: KASAN: slab-use-after-free in mlx5e_rep_neigh_entry_release+0x109/0x3a0 [mlx5_core]
[ 2453.379125] Read of size 4 at addr ffff888127af9008 by task modprobe/2496
[ 2453.381542] CPU: 7 PID: 2496 Comm: modprobe Tainted: G B 6.4.0-rc7+ #15
[ 2453.383386] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 2453.384335] Call Trace:
[ 2453.384625] <TASK>
[ 2453.384891] dump_stack_lvl+0x33/0x50
[ 2453.385285] print_report+0xc2/0x610
[ 2453.385667] ? __virt_addr_valid+0xb1/0x130
[ 2453.386091] ? mlx5e_rep_neigh_entry_release+0x109/0x3a0 [mlx5_core]
[ 2453.386757] kasan_report+0xae/0xe0
[ 2453.387123] ? mlx5e_rep_neigh_entry_release+0x109/0x3a0 [mlx5_core]
[ 2453.387798] mlx5e_rep_neigh_entry_release+0x109/0x3a0 [mlx5_core]
[ 2453.388465] mlx5e_rep_encap_entry_detach+0xa6/0xe0 [mlx5_core]
[ 2453.389111] mlx5e_encap_dealloc+0xa7/0x100 [mlx5_core]
[ 2453.389706] mlx5e_tc_tun_encap_dests_unset+0x61/0xb0 [mlx5_core]
[ 2453.390361] mlx5_free_flow_attr_actions+0x11e/0x340 [mlx5_core]
[ 2453.391015] ? complete_all+0x43/0xd0
[ 2453.391398] ? free_flow_post_acts+0x38/0x120 [mlx5_core]
[ 2453.392004] mlx5e_tc_del_fdb_flow+0x4ae/0x690 [mlx5_core]
[ 2453.392618] mlx5e_tc_del_fdb_peers_flow+0x308/0x370 [mlx5_core]
[ 2453.393276] mlx5e_tc_clean_fdb_peer_flows+0xf5/0x140 [mlx5_core]
[ 2453.393925] mlx5_esw_offloads_unpair+0x86/0x540 [mlx5_core]
[ 2453.394546] ? mlx5_esw_offloads_set_ns_peer.isra.0+0x180/0x180 [mlx5_core]
[ 2453.395268] ? down_write+0xaa/0x100
[ 2453.395652] mlx5_esw_offloads_devcom_event+0x203/0x530 [mlx5_core]
[ 2453.396317] mlx5_devcom_send_event+0xbb/0x190 [mlx5_core]
[ 2453.396917] mlx5_esw_offloads_devcom_cleanup+0xb0/0xd0 [mlx5_core]
[ 2453.397582] mlx5e_tc_esw_cleanup+0x42/0x120 [mlx5_core]
[ 2453.398182] mlx5e_rep_tc_cleanup+0x15/0x30 [mlx5_core]
[ 2453.398768] mlx5e_cleanup_rep_tx+0x6c/0x80 [mlx5_core]
[ 2453.399367] mlx5e_detach_netdev+0xee/0x120 [mlx5_core]
[ 2453.399957] mlx5e_netdev_change_profile+0x84/0x170 [mlx5_core]
[ 2453.400598] mlx5e_vport_rep_unload+0xe0/0xf0 [mlx5_core]
[ 2453.403781] mlx5_eswitch_unregister_vport_reps+0x15e/0x190 [mlx5_core]
[ 2453.404479] ? mlx5_eswitch_register_vport_reps+0x200/0x200 [mlx5_core]
[ 2453.405170] ? up_write+0x39/0x60
[ 2453.405529] ? kernfs_remove_by_name_ns+0xb7/0xe0
[ 2453.405985] auxiliary_bus_remove+0x2e/0x40
[ 2453.406405] device_release_driver_internal+0x243/0x2d0
[ 2453.406900] ? kobject_put+0x42/0x2d0
[ 2453.407284] bus_remove_device+0x128/0x1d0
[ 2453.407687] device_del+0x240/0x550
[ 2453.408053] ? waiting_for_supplier_show+0xe0/0xe0
[ 2453.408511] ? kobject_put+0xfa/0x2d0
[ 2453.408889] ? __kmem_cache_free+0x14d/0x280
[ 2453.409310] mlx5_rescan_drivers_locked.part.0+0xcd/0x2b0 [mlx5_core]
[ 2453.409973] mlx5_unregister_device+0x40/0x50 [mlx5_core]
[ 2453.410561] mlx5_uninit_one+0x3d/0x110 [mlx5_core]
[ 2453.411111] remove_one+0x89/0x130 [mlx5_core]
[ 24
---truncated---
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Analysis
by VulDB Data Team • 01/03/2026
The vulnerability described in CVE-2023-54148 resides within the Linux kernel's mlx5 core driver, specifically impacting the Mellanox ConnectX network adapter family. This issue manifests as a use-after-free error during the cleanup process of network representation devices in an ECMP (Equal-Cost Multipath) IP tunnel encapsulation environment. The flaw occurs when multiple eswitch instances are involved in offloading traffic flows, particularly when one eswitch instance unloads its driver while another still references neighbor information from a peer eswitch.
The technical root cause involves improper ordering of cleanup operations within the mlx5 driver's network offloading subsystem. When an eswitch instance unpairs from the devcom framework, typically during driver unloading, the cleanup_tx callback is invoked in a sequence that precedes the proper cleanup of neighbor entries. This misordering leads to a situation where neighbor information is freed in the uplink's profile cleanup routine before being accessed during peer rule deletion, triggering a slab-use-after-free condition as reported by KASAN. The call trace demonstrates the execution path leading to mlx5e_rep_neigh_entry_release being called on already freed memory, specifically at address ffff888127af9008.
The operational impact of this vulnerability is significant for systems utilizing Mellanox network adapters in complex networking configurations involving ECMP and IP tunneling. The use-after-free condition can result in system instability, kernel panics, or potential privilege escalation depending on the exploitation vector. Systems running kernel versions with the affected mlx5 driver code are at risk, particularly when managing network flows that traverse multiple eswitch instances in ECMP mode. The vulnerability is especially concerning in high-availability environments where driver unloading and reloading operations are common.
The fix implemented addresses the timing issue by repositioning the neighbor cleanup operations to occur within the profile's cleanup_tx callback, ensuring proper ordering relative to other cleanup operations. This change moves the neighbor information initialization to the init_tx callback for symmetry, while ensuring that cleanup operations happen after the mlx5e_cleanup_uplink_rep_tx function is called. The solution aligns with the established pattern of maintaining proper resource lifecycle management in kernel networking drivers, preventing premature deallocation of resources that may still be referenced during cleanup sequences. This remediation follows the principles outlined in CWE-415, which addresses double free conditions and improper resource management, and aligns with ATT&CK techniques related to privilege escalation through kernel vulnerabilities. The fix ensures that neighbor entries are properly managed during the complete lifecycle of network representation devices, preventing the race condition that led to the use-after-free error in the mlx5 driver's ECMP tunnel encapsulation implementation.