Linux Kernel up to 6.3.5 mlx5_add_flow_rules use after free

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel up to 6.3.5. Affected by this vulnerability is the function mlx5_add_flow_rules. The manipulation results in use after free. This vulnerability is identified as CVE-2023-54216. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.3.5. Affected is the function mlx5_add_flow_rules. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: TC, Fix using eswitch mapping in nic mode Cited patch is using the eswitch object mapping pool while in nic mode where it isn't initialized. This results in the trace below [0]. Fix that by using either nic or eswitch object mapping pool depending if eswitch is enabled or not. [0]: [ 826.446057] ================================================================== [ 826.446729] BUG: KASAN: slab-use-after-free in mlx5_add_flow_rules+0x30/0x490 [mlx5_core] [ 826.447515] Read of size 8 at addr ffff888194485830 by task tc/6233 [ 826.448243] CPU: 16 PID: 6233 Comm: tc Tainted: G W 6.3.0-rc6+ #1 [ 826.448890] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 826.449785] Call Trace: [ 826.450052] <TASK> [ 826.450302] dump_stack_lvl+0x33/0x50 [ 826.450650] print_report+0xc2/0x610 [ 826.450998] ? __virt_addr_valid+0xb1/0x130 [ 826.451385] ? mlx5_add_flow_rules+0x30/0x490 [mlx5_core] [ 826.451935] kasan_report+0xae/0xe0 [ 826.452276] ? mlx5_add_flow_rules+0x30/0x490 [mlx5_core] [ 826.452829] mlx5_add_flow_rules+0x30/0x490 [mlx5_core] [ 826.453368] ? __kmalloc_node+0x5a/0x120 [ 826.453733] esw_add_restore_rule+0x20f/0x270 [mlx5_core] [ 826.454288] ? mlx5_eswitch_add_send_to_vport_meta_rule+0x260/0x260 [mlx5_core] [ 826.455011] ? mutex_unlock+0x80/0xd0 [ 826.455361] ? __mutex_unlock_slowpath.constprop.0+0x210/0x210 [ 826.455862] ? mapping_add+0x2cb/0x440 [mlx5_core] [ 826.456425] mlx5e_tc_action_miss_mapping_get+0x139/0x180 [mlx5_core] [ 826.457058] ? mlx5e_tc_update_skb_nic+0xb0/0xb0 [mlx5_core] [ 826.457636] ? __kasan_kmalloc+0x77/0x90 [ 826.458000] ? __kmalloc+0x57/0x120 [ 826.458336] mlx5_tc_ct_flow_offload+0x325/0xe40 [mlx5_core] [ 826.458916] ? ct_kernel_enter.constprop.0+0x48/0xa0 [ 826.459360] ? mlx5_tc_ct_parse_action+0xf0/0xf0 [mlx5_core] [ 826.459933] ? mlx5e_mod_hdr_attach+0x491/0x520 [mlx5_core] [ 826.460507] ? mlx5e_mod_hdr_get+0x12/0x20 [mlx5_core] [ 826.461046] ? mlx5e_tc_attach_mod_hdr+0x154/0x170 [mlx5_core] [ 826.461635] mlx5e_configure_flower+0x969/0x2110 [mlx5_core] [ 826.462217] ? _raw_spin_lock_bh+0x85/0xe0 [ 826.462597] ? __mlx5e_add_fdb_flow+0x750/0x750 [mlx5_core] [ 826.463163] ? kasan_save_stack+0x2e/0x40 [ 826.463534] ? down_read+0x115/0x1b0 [ 826.463878] ? down_write_killable+0x110/0x110 [ 826.464288] ? tc_setup_action.part.0+0x9f/0x3b0 [ 826.464701] ? mlx5e_is_uplink_rep+0x4c/0x90 [mlx5_core] [ 826.465253] ? mlx5e_tc_reoffload_flows_work+0x130/0x130 [mlx5_core] [ 826.465878] tc_setup_cb_add+0x112/0x250 [ 826.466247] fl_hw_replace_filter+0x230/0x310 [cls_flower] [ 826.466724] ? fl_hw_destroy_filter+0x1a0/0x1a0 [cls_flower] [ 826.467212] fl_change+0x14e1/0x2030 [cls_flower] [ 826.467636] ? sock_def_readable+0x89/0x120 [ 826.468019] ? fl_tmplt_create+0x2d0/0x2d0 [cls_flower] [ 826.468509] ? kasan_unpoison+0x23/0x50 [ 826.468873] ? get_random_u16+0x180/0x180 [ 826.469244] ? __radix_tree_lookup+0x2b/0x130 [ 826.469640] ? fl_get+0x7b/0x140 [cls_flower] [ 826.470042] ? fl_mask_put+0x200/0x200 [cls_flower] [ 826.470478] ? __mutex_unlock_slowpath.constprop.0+0x210/0x210 [ 826.470973] ? fl_tmplt_create+0x2d0/0x2d0 [cls_flower] [ 826.471427] tc_new_tfilter+0x644/0x1050 [ 826.471795] ? tc_get_tfilter+0x860/0x860 [ 826.472170] ? __thaw_task+0x130/0x130 [ 826.472525] ? arch_stack_walk+0x98/0xf0 [ 826.472892] ? cap_capable+0x9f/0xd0 [ 826.473235] ? security_capable+0x47/0x60 [ 826.473608] rtnetlink_rcv_msg+0x1d5/0x550 [ 826.473985] ? rtnl_calcit.isra.0+0x1f0/0x1f0 [ 826.474383] ? __stack_depot_save+0x35/0x4c0 [ 826.474779] ? kasan_save_stack+0x2e/0x40 [ 826.475149] ? kasan_save_stack+0x1e/0x40 [ 826.475518] ? __kasan_record_aux_stack+0x9f/0xb0 [ 826.475939] ? task_work_add+0x77/0x1c0 [ 826.476305] netlink_rcv_skb+0xe0/0x210 ---truncated---

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2023-54216 since 12/30/2025. The exploitability is told to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 04/26/2026).

Upgrading to version 6.3.6 eliminates this vulnerability. Applying the patch 4150441c010dec36abc389828e2e4758bd8ad4b3/dfa1e46d6093831b9d49f0f350227a1d13644a2f is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2025-2941). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Debian Linux
• Amazon Linux 2
• IBM Power Hardware Management Console
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• Open Source Linux Kernel
• RESF Rocky Linux
• IBM DataPower Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.3.0
• 6.3.1
• 6.3.2
• 6.3.3
• 6.3.4
• 6.3.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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