{"id":"DEBIAN-CVE-2026-68377","details":"In 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-\u003etcft_enc_metadata-\u003edst) after the writer's dst_release has already pushed the dst's rcuref to RCUREF_DEAD.  zdi-disclosures@trendmicro.com 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:  \u003cTASK\u003e  __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---","modified":"2026-09-14T17:03:46.542874112Z","published":"2026-08-10T13:20:30.647Z","upstream":["CVE-2026-68377"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-68377"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.187-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.170-1","6.1.170-2","6.1.170-3","6.1.172-1","6.1.174-1","6.1.176-1","6.1.177-1","6.1.180-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not 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