In the Linux kernel, the following vulnerability has been resolved:

net/sched: cls_api: remove block_cb from driver_list before freeing

Error handler of tcf_block_bind() frees the whole bo->cb_list on error.
However, by that time the flow_block_cb instances are already in the driver
list because driver ndo_setup_tc() callback is called before that up the
call chain in tcf_block_offload_cmd(). This leaves dangling pointers to
freed objects in the list and causes use-after-free[0]. Fix it by also
removing flow_block_cb instances from driver_list before deallocating them.

[0]:
[ 279.868433] ==================================================================
[ 279.869964] BUG: KASAN: slab-use-after-free in flow_block_cb_setup_simple+0x631/0x7c0
[ 279.871527] Read of size 8 at addr ffff888147e2bf20 by task tc/2963

[ 279.873151] CPU: 6 PID: 2963 Comm: tc Not tainted 6.3.0-rc6+ #4
[ 279.874273] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 279.876295] Call Trace:
[ 279.876882] <TASK>
[ 279.877413] dump_stack_lvl+0x33/0x50
[ 279.878198] print_report+0xc2/0x610
[ 279.878987] ? flow_block_cb_setup_simple+0x631/0x7c0
[ 279.879994] kasan_report+0xae/0xe0
[ 279.880750] ? flow_block_cb_setup_simple+0x631/0x7c0
[ 279.881744] ? mlx5e_tc_reoffload_flows_work+0x240/0x240 [mlx5_core]
[ 279.883047] flow_block_cb_setup_simple+0x631/0x7c0
[ 279.884027] tcf_block_offload_cmd.isra.0+0x189/0x2d0
[ 279.885037] ? tcf_block_setup+0x6b0/0x6b0
[ 279.885901] ? mutex_lock+0x7d/0xd0
[ 279.886669] ? __mutex_unlock_slowpath.constprop.0+0x2d0/0x2d0
[ 279.887844] ? ingress_init+0x1c0/0x1c0 [sch_ingress]
[ 279.888846] tcf_block_get_ext+0x61c/0x1200
[ 279.889711] ingress_init+0x112/0x1c0 [sch_ingress]
[ 279.890682] ? clsact_init+0x2b0/0x2b0 [sch_ingress]
[ 279.891701] qdisc_create+0x401/0xea0
[ 279.892485] ? qdisc_tree_reduce_backlog+0x470/0x470
[ 279.893473] tc_modify_qdisc+0x6f7/0x16d0
[ 279.894344] ? tc_get_qdisc+0xac0/0xac0
[ 279.895213] ? mutex_lock+0x7d/0xd0
[ 279.896005] ? __mutex_lock_slowpath+0x10/0x10
[ 279.896910] rtnetlink_rcv_msg+0x5fe/0x9d0
[ 279.897770] ? rtnl_calcit.isra.0+0x2b0/0x2b0
[ 279.898672] ? __sys_sendmsg+0xb5/0x140
[ 279.899494] ? do_syscall_64+0x3d/0x90
[ 279.900302] ? entry_SYSCALL_64_after_hwframe+0x46/0xb0
[ 279.901337] ? kasan_save_stack+0x2e/0x40
[ 279.902177] ? kasan_save_stack+0x1e/0x40
[ 279.903058] ? kasan_set_track+0x21/0x30
[ 279.903913] ? kasan_save_free_info+0x2a/0x40
[ 279.904836] ? ____kasan_slab_free+0x11a/0x1b0
[ 279.905741] ? kmem_cache_free+0x179/0x400
[ 279.906599] netlink_rcv_skb+0x12c/0x360
[ 279.907450] ? rtnl_calcit.isra.0+0x2b0/0x2b0
[ 279.908360] ? netlink_ack+0x1550/0x1550
[ 279.909192] ? rhashtable_walk_peek+0x170/0x170
[ 279.910135] ? kmem_cache_alloc_node+0x1af/0x390
[ 279.911086] ? _copy_from_iter+0x3d6/0xc70
[ 279.912031] netlink_unicast+0x553/0x790
[ 279.912864] ? netlink_attachskb+0x6a0/0x6a0
[ 279.913763] ? netlink_recvmsg+0x416/0xb50
[ 279.914627] netlink_sendmsg+0x7a1/0xcb0
[ 279.915473] ? netlink_unicast+0x790/0x790
[ 279.916334] ? iovec_from_user.part.0+0x4d/0x220
[ 279.917293] ? netlink_unicast+0x790/0x790
[ 279.918159] sock_sendmsg+0xc5/0x190
[ 279.918938] ____sys_sendmsg+0x535/0x6b0
[ 279.919813] ? import_iovec+0x7/0x10
[ 279.920601] ? kernel_sendmsg+0x30/0x30
[ 279.921423] ? __copy_msghdr+0x3c0/0x3c0
[ 279.922254] ? import_iovec+0x7/0x10
[ 279.923041] ___sys_sendmsg+0xeb/0x170
[ 279.923854] ? copy_msghdr_from_user+0x110/0x110
[ 279.924797] ? ___sys_recvmsg+0xd9/0x130
[ 279.925630] ? __perf_event_task_sched_in+0x183/0x470
[ 279.926656] ? ___sys_sendmsg+0x170/0x170
[ 279.927529] ? ctx_sched_in+0x530/0x530
[ 279.928369] ? update_curr+0x283/0x4f0
[ 279.929185] ? perf_event_update_userpage+0x570/0x570
[ 279.930201] ? __fget_light+0x57/0x520
[ 279.931023] ? __switch_to+0x53d/0xe70
[ 27
---truncated---

No CVSS v4.0

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00035.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Linux Linux unaffected
Version Status Constraints
59094b1e5094c7e50a3d2912202fd30b6a1dadf8 affected < cc5fe387c6294d0471cb7ed064efac97fac65ccc
59094b1e5094c7e50a3d2912202fd30b6a1dadf8 affected < 7311c8be3755611bf6edea4dfbeb190b4bdd489f
59094b1e5094c7e50a3d2912202fd30b6a1dadf8 affected < cb145932fcf6814e7e95e467eb70e7849a845ae9
59094b1e5094c7e50a3d2912202fd30b6a1dadf8 affected < 55866fe3fded3ce94ac3fc1bb3dfce654282f483
59094b1e5094c7e50a3d2912202fd30b6a1dadf8 affected < 26aec72429a05e917d574eca0efc5306c63a8862
59094b1e5094c7e50a3d2912202fd30b6a1dadf8 affected < 7b7a74ed303d532fb73ae4b1697f16a0fea89cd0
59094b1e5094c7e50a3d2912202fd30b6a1dadf8 affected < da94a7781fc3c92e7df7832bc2746f4d39bc624e
Linux Linux affected
Version Status Constraints
5.3 affected —
0 unaffected < 5.3
5.4.243 unaffected ≤ 5.4.*
5.10.180 unaffected ≤ 5.10.*
5.15.112 unaffected ≤ 5.15.*
6.1.29 unaffected ≤ 6.1.*
6.2.16 unaffected ≤ 6.2.*
6.3.3 unaffected ≤ 6.3.*
6.4 unaffected ≤ *

No data.

No data.

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://git.kernel.org/stable/c/26aec72429a05e917d574eca0efc5306c63a8862 cve-icon cve-icon
https://git.kernel.org/stable/c/55866fe3fded3ce94ac3fc1bb3dfce654282f483 cve-icon cve-icon
https://git.kernel.org/stable/c/7311c8be3755611bf6edea4dfbeb190b4bdd489f cve-icon cve-icon
https://git.kernel.org/stable/c/7b7a74ed303d532fb73ae4b1697f16a0fea89cd0 cve-icon cve-icon
https://git.kernel.org/stable/c/cb145932fcf6814e7e95e467eb70e7849a845ae9 cve-icon cve-icon
https://git.kernel.org/stable/c/cc5fe387c6294d0471cb7ed064efac97fac65ccc cve-icon cve-icon
https://git.kernel.org/stable/c/da94a7781fc3c92e7df7832bc2746f4d39bc624e cve-icon cve-icon
https://lore.kernel.org/linux-cve-announce/2025123028-CVE-2023-54193-50c4@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2023-54193 cve-icon
https://www.cve.org/CVERecord?id=CVE-2023-54193 cve-icon
History

Wed, 31 Dec 2025 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important

Tue, 30 Dec 2025 12:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_api: remove block_cb from driver_list before freeing Error handler of tcf_block_bind() frees the whole bo->cb_list on error. However, by that time the flow_block_cb instances are already in the driver list because driver ndo_setup_tc() callback is called before that up the call chain in tcf_block_offload_cmd(). This leaves dangling pointers to freed objects in the list and causes use-after-free[0]. Fix it by also removing flow_block_cb instances from driver_list before deallocating them. [0]: [ 279.868433] ================================================================== [ 279.869964] BUG: KASAN: slab-use-after-free in flow_block_cb_setup_simple+0x631/0x7c0 [ 279.871527] Read of size 8 at addr ffff888147e2bf20 by task tc/2963 [ 279.873151] CPU: 6 PID: 2963 Comm: tc Not tainted 6.3.0-rc6+ #4 [ 279.874273] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 279.876295] Call Trace: [ 279.876882] <TASK> [ 279.877413] dump_stack_lvl+0x33/0x50 [ 279.878198] print_report+0xc2/0x610 [ 279.878987] ? flow_block_cb_setup_simple+0x631/0x7c0 [ 279.879994] kasan_report+0xae/0xe0 [ 279.880750] ? flow_block_cb_setup_simple+0x631/0x7c0 [ 279.881744] ? mlx5e_tc_reoffload_flows_work+0x240/0x240 [mlx5_core] [ 279.883047] flow_block_cb_setup_simple+0x631/0x7c0 [ 279.884027] tcf_block_offload_cmd.isra.0+0x189/0x2d0 [ 279.885037] ? tcf_block_setup+0x6b0/0x6b0 [ 279.885901] ? mutex_lock+0x7d/0xd0 [ 279.886669] ? __mutex_unlock_slowpath.constprop.0+0x2d0/0x2d0 [ 279.887844] ? ingress_init+0x1c0/0x1c0 [sch_ingress] [ 279.888846] tcf_block_get_ext+0x61c/0x1200 [ 279.889711] ingress_init+0x112/0x1c0 [sch_ingress] [ 279.890682] ? clsact_init+0x2b0/0x2b0 [sch_ingress] [ 279.891701] qdisc_create+0x401/0xea0 [ 279.892485] ? qdisc_tree_reduce_backlog+0x470/0x470 [ 279.893473] tc_modify_qdisc+0x6f7/0x16d0 [ 279.894344] ? tc_get_qdisc+0xac0/0xac0 [ 279.895213] ? mutex_lock+0x7d/0xd0 [ 279.896005] ? __mutex_lock_slowpath+0x10/0x10 [ 279.896910] rtnetlink_rcv_msg+0x5fe/0x9d0 [ 279.897770] ? rtnl_calcit.isra.0+0x2b0/0x2b0 [ 279.898672] ? __sys_sendmsg+0xb5/0x140 [ 279.899494] ? do_syscall_64+0x3d/0x90 [ 279.900302] ? entry_SYSCALL_64_after_hwframe+0x46/0xb0 [ 279.901337] ? kasan_save_stack+0x2e/0x40 [ 279.902177] ? kasan_save_stack+0x1e/0x40 [ 279.903058] ? kasan_set_track+0x21/0x30 [ 279.903913] ? kasan_save_free_info+0x2a/0x40 [ 279.904836] ? ____kasan_slab_free+0x11a/0x1b0 [ 279.905741] ? kmem_cache_free+0x179/0x400 [ 279.906599] netlink_rcv_skb+0x12c/0x360 [ 279.907450] ? rtnl_calcit.isra.0+0x2b0/0x2b0 [ 279.908360] ? netlink_ack+0x1550/0x1550 [ 279.909192] ? rhashtable_walk_peek+0x170/0x170 [ 279.910135] ? kmem_cache_alloc_node+0x1af/0x390 [ 279.911086] ? _copy_from_iter+0x3d6/0xc70 [ 279.912031] netlink_unicast+0x553/0x790 [ 279.912864] ? netlink_attachskb+0x6a0/0x6a0 [ 279.913763] ? netlink_recvmsg+0x416/0xb50 [ 279.914627] netlink_sendmsg+0x7a1/0xcb0 [ 279.915473] ? netlink_unicast+0x790/0x790 [ 279.916334] ? iovec_from_user.part.0+0x4d/0x220 [ 279.917293] ? netlink_unicast+0x790/0x790 [ 279.918159] sock_sendmsg+0xc5/0x190 [ 279.918938] ____sys_sendmsg+0x535/0x6b0 [ 279.919813] ? import_iovec+0x7/0x10 [ 279.920601] ? kernel_sendmsg+0x30/0x30 [ 279.921423] ? __copy_msghdr+0x3c0/0x3c0 [ 279.922254] ? import_iovec+0x7/0x10 [ 279.923041] ___sys_sendmsg+0xeb/0x170 [ 279.923854] ? copy_msghdr_from_user+0x110/0x110 [ 279.924797] ? ___sys_recvmsg+0xd9/0x130 [ 279.925630] ? __perf_event_task_sched_in+0x183/0x470 [ 279.926656] ? ___sys_sendmsg+0x170/0x170 [ 279.927529] ? ctx_sched_in+0x530/0x530 [ 279.928369] ? update_curr+0x283/0x4f0 [ 279.929185] ? perf_event_update_userpage+0x570/0x570 [ 279.930201] ? __fget_light+0x57/0x520 [ 279.931023] ? __switch_to+0x53d/0xe70 [ 27 ---truncated---
Title net/sched: cls_api: remove block_cb from driver_list before freeing
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-12-30T12:09:00.738Z

Reserved: 2025-12-30T12:06:44.498Z

Link: CVE-2023-54193

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2025-12-30T13:16:07.320

Modified: 2025-12-31T20:43:05.160

Link: CVE-2023-54193

cve-icon Redhat

Severity : Important

Publid Date: 2025-12-30T00:00:00Z

Links: CVE-2023-54193 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses

No weakness.