CVE-2026-80739
Received Received - Intake

Deadlock in Linux Kernel MLX5e TC Flow Handling

Publication date: 2026-09-03

Last updated on: 2026-09-03

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: TC, Check if flow is PEER before acquiring devcom lock In case __mlx5e_add_fdb_flow() fails in lower levels, the flow is deleted via mlx5e_tc_del_flow(), and mlx5e_tc_del_flow() is acquiring ESW devcom lock without condition. In addition, in case of peer_flow, __mlx5e_add_fdb_flow() is called while holding ESW devcom comp lock. This results in an AA deadlock. To fix this, introduce a new PEER flag that is set on flows created as peer flows (the duplicate flows on peer devices), and check it in mlx5e_tc_del_flow() before acquiring ESW devcom lock. Lockdep splat: ============================================ WARNING: possible recursive locking detected ============================================ Possible unsafe locking scenario: CPU0 ---- lock(&comp->lock_key#2); lock(&comp->lock_key#2); *** DEADLOCK *** Call Trace: <TASK> dump_stack_lvl+0x69/0xa0 print_deadlock_bug.cold+0xbd/0xca __lock_acquire+0x1671/0x2ec0 lock_acquire+0x10e/0x2e0 down_read+0x95/0x430 mlx5_devcom_for_each_peer_begin+0x4e/0xe0 [mlx5_core] mlx5e_tc_del_flow+0x11d/0xa70 [mlx5_core] mlx5e_flow_put+0x99/0x100 [mlx5_core] __mlx5e_add_fdb_flow+0x409/0xf00 [mlx5_core] mlx5e_configure_flower+0x2a86/0x4100 [mlx5_core] mlx5e_rep_setup_tc_cls_flower+0x12f/0x1b0 [mlx5_core] mlx5e_rep_setup_tc_cb+0x153/0x750 [mlx5_core] tc_setup_cb_add+0x1dc/0x470 fl_change+0x2f4d/0x626d [cls_flower] tc_new_tfilter+0x79b/0x2310 rtnetlink_rcv_msg+0x778/0xad0 do_syscall_64+0x70/0x960 entry_SYSCALL_64_after_hwframe+0x4b/0x53 </TASK>

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Meta Information

Published
2026-09-03
Last Modified
2026-09-03
Generated
2026-09-03
AI Q&A
2026-09-03
EPSS Evaluated
N/A
NVD
CVE-2026-80739
EUVD
EUVD-2026-70343

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
mlx5_core mlx5e *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves a deadlock issue in the mlx5e driver for Mellanox ConnectX network adapters. When a flow fails during creation, the cleanup process attempts to acquire a lock without checking if the flow is a peer flow, leading to a recursive locking scenario and a deadlock.

Detection Guidance

This vulnerability is specific to the Linux kernel's mlx5e driver and involves a deadlock scenario in network flow handling. Detection requires checking kernel logs for lockdep warnings or stack traces related to mlx5e_tc_del_flow or mlx5_devcom_for_each_peer_begin. Monitor for kernel warnings during network flow operations.

Impact Analysis

This vulnerability can cause system hangs or crashes due to deadlocks, potentially disrupting network traffic and services relying on the affected driver. Systems using Mellanox ConnectX adapters with mlx5e driver may experience instability.

Mitigation Strategies

Apply the latest kernel update that includes the fix for this vulnerability. If immediate patching is not possible, avoid creating peer flows in mlx5e driver configurations until the update is applied. Monitor kernel logs for deadlock warnings as a sign of exploitation.

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