net/sched: act_tunnel_key: Defer dst_release to RCU callback

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-68377
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-10 13:20:30 UTC
Updated2026-08-19 17:20:47 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/sched: act_tunnel_key: Defer dst_release to RCU callback Fix a race-condition use-after-free in tunnel_key_release_params(). The function releases the metadata_dst of the old params synchronously via dst_release() while deferring the params struct free with kfree_rcu(). A concurrent tunnel_key_act() reader on the datapath may still hold the old params pointer (under rcu_read_lock_bh) and proceed to call dst_clone(&params->tcft_enc_metadata->dst) after the writer's dst_release has already pushed the dst's rcuref to RCUREF_DEAD. [email protected] produced a poc which i (and Victor) verified that KASAN reports: ================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:112 BUG: KASAN: slab-use-after-free in atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326 BUG: KASAN: slab-use-after-free in __rcuref_put include/linux/rcuref.h:109 BUG: KASAN: slab-use-after-free in rcuref_put include/linux/rcuref.h:173 BUG: KASAN: slab-use-after-free in dst_release+0x5b/0x370 net/core/dst.c:168 Write of size 4 at addr ffff88806158de40 by task poc/9388 CPU: 0 UID: 0 PID: 9388 Comm: poc Tainted: G W 7.1.0-rc7 #7 PREEMPT(lazy) Tainted: [W]=WARN Hardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 print_report+0x139/0x4ad mm/kasan/report.c:482 kasan_report+0xe4/0x1d0 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:186 kasan_check_range+0x125/0x200 mm/kasan/generic.c:200 instrument_atomic_read_write include/linux/instrumented.h:112 atomic_sub_return_release include/linux/atomic/atomic-instrumented.h:326 __rcuref_put include/linux/rcuref.h:109 rcuref_put include/linux/rcuref.h:173 dst_release+0x5b/0x370 net/core/dst.c:168 refdst_drop include/net/dst.h:272 skb_dst_drop include/net/dst.h:284 skb_release_head_state+0x293/0x400 net/core/skbuff.c:1163 skb_release_all net/core/skbuff.c:1187 [..] Allocated by task 9391: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 __kasan_kmalloc+0x9a/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 __do_kmalloc_node mm/slub.c:5296 __kmalloc_noprof+0x2f1/0x830 mm/slub.c:5308 kmalloc_noprof include/linux/slab.h:954 kzalloc_noprof include/linux/slab.h:1188 offload_action_alloc+0x2f/0x130 net/core/flow_offload.c:35 tcf_action_offload_add_ex+0x1ba/0x880 net/sched/act_api.c:258 tcf_action_offload_add net/sched/act_api.c:293 tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101 [..] Freed by task 9391: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 __kasan_slab_free+0x6b/0x90 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 slab_free_hook mm/slub.c:2689 slab_free mm/slub.c:6251 kfree+0x21f/0x6b0 mm/slub.c:6566 tcf_action_offload_add_ex+0x4ad/0x880 net/sched/act_api.c:284 tcf_action_offload_add net/sched/act_api.c:293 tcf_action_init+0x66e/0xa20 net/sched/act_api.c:1547 tcf_action_add+0xf6/0x5d0 net/sched/act_api.c:2101 The buggy address belongs to the object at ffff88806158de00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 64 bytes inside of freed 256-byte region [ffff88806158de00, ffff88806158df00) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88806158d600 pfn:0x6158c head: order:1 mapcount:0 entire_map ---truncated---

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001270000 probability, percentile 0.027850000 (date 2026-08-19)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 9174c3df1cd181c14913138d50ccbe539bb08335 b5931f020b681fdcb9378262d89b61cb3c7ebbf8 git Not specified
CNA Linux Linux affected 9174c3df1cd181c14913138d50ccbe539bb08335 389d03992dabb80488228e8119b9dd6d0f58e1a6 git Not specified
CNA Linux Linux affected 9174c3df1cd181c14913138d50ccbe539bb08335 676ad6aa7cec89a08d2a5ce3cd5959e313f29733 git Not specified
CNA Linux Linux affected 9174c3df1cd181c14913138d50ccbe539bb08335 531dbb5bb98e52ad26be7e90f9f8bec707c5bd0e git Not specified
CNA Linux Linux affected 9174c3df1cd181c14913138d50ccbe539bb08335 2200a00ff247f70f5dcdb4e6f14b0d48ddac5467 git Not specified
CNA Linux Linux affected 9174c3df1cd181c14913138d50ccbe539bb08335 fed1b1ddab41a0e7a462ac690a0c8af6ff793624 git Not specified
CNA Linux Linux affected 9174c3df1cd181c14913138d50ccbe539bb08335 2791a501da508b704a617b4dba29db54a65bc9f7 git Not specified
CNA Linux Linux affected 9174c3df1cd181c14913138d50ccbe539bb08335 f1f5c8a3955f8fda3f84ed883ac8daa1847e724c git Not specified
CNA Linux Linux affected 02239e797ac75f89a05622a27d04695f08c1ca89 git Not specified
CNA Linux Linux affected ca9b7a65a2c97579fcdd509d454d48e3a5c49af8 git Not specified
CNA Linux Linux affected 4.19.19 4.20 semver Not specified
CNA Linux Linux affected 4.20.6 4.21 semver Not specified
CNA Linux Linux affected 5.0 Not specified
CNA Linux Linux unaffected 5.0 semver Not specified
CNA Linux Linux unaffected 5.10.265 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.148 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.101 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.42 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.6 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/f1f5c8a3955f8fda3f84ed883ac8daa1847e724c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2200a00ff247f70f5dcdb4e6f14b0d48ddac5467 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/531dbb5bb98e52ad26be7e90f9f8bec707c5bd0e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/676ad6aa7cec89a08d2a5ce3cd5959e313f29733 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/389d03992dabb80488228e8119b9dd6d0f58e1a6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2791a501da508b704a617b4dba29db54a65bc9f7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fed1b1ddab41a0e7a462ac690a0c8af6ff793624 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b5931f020b681fdcb9378262d89b61cb3c7ebbf8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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