CVE-2023-54148
Description
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] [ 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---
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A Linux kernel use-after-free in mlx5e's neighbour cleanup due to wrong ordering for ECMP encap rules, fixed by moving cleanup to profile->cleanup_tx callback.
What the vulnerability is
In the Linux kernel's mlx5e driver, a use-after-free bug occurs when handling IP tunnel encapsulation in Equal-Cost Multipath (ECMP) mode. When a flow is duplicated to a peer eswitch, neighbour information on the peer uplink representor is created. A previous commit moved eswitch devcom unpair to the uplink unload API (profile->cleanup_tx), but the neighbour cleanup was executed earlier in the profile->disable callback. This ordering error causes the neighbour entry to be freed before the peer rule deletion attempts to access it, leading to a slab-use-after-free.
How it is exploited
An attacker who can trigger driver unload (e.g., by unloading the mlx5_core module) on a system with an offloaded ECMP encapsulation rule can cause a use-after-free. The exploit does not require network access but requires the ability to load/unload kernel modules or otherwise trigger the error path. The KASAN report shows a read of size 4 on freed memory during mlx5e_rep_neigh_entry_release, triggered from mlx5e_rep_encap_entry_detach when deleting the peer rule.
Impact
An attacker achieving this use-after-free could potentially corrupt kernel memory, leading to system crash or privilege escalation. The KASAN log indicates a BUG: KASAN: slab-use-after-free with a call trace showing the corrupted access at mlx5e_rep_neigh_entry_release+0x109.
Mitigation status
This vulnerability is fixed in the Linux kernel by commit 36697c592cd0 ("net/mlx5e: Move representor neigh cleanup to profile cleanup_tx"), which moves neighbour cleanup to the profile->cleanup_tx callback, after mlx5e_cleanup_uplink_rep_tx is called, and moves neighbour init to the init_tx callback for symmetry. Systems running kernel versions before this fix are vulnerable; updates should be applied [1].
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
1Patches
3d628ba98eb1636697c592cd0d03b6e6f3182Vulnerability mechanics
Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
3News mentions
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