==================================================================
BUG: KASAN: use-after-free in skb_clear_hash include/linux/skbuff.h:1317 [inline]
BUG: KASAN: use-after-free in tcf_ct_handle_fragments net/sched/act_ct.c:768 [inline]
BUG: KASAN: use-after-free in tcf_ct_act+0x361f/0x3b40 net/sched/act_ct.c:1012
Write of size 4 at addr ffff888023080a94 by task syz.1.71/4532

CPU: 1 PID: 4532 Comm: syz.1.71 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 skb_clear_hash include/linux/skbuff.h:1317 [inline]
 tcf_ct_handle_fragments net/sched/act_ct.c:768 [inline]
 tcf_ct_act+0x361f/0x3b40 net/sched/act_ct.c:1012
 tcf_action_exec+0x177/0x570 net/sched/act_api.c:761
 __tcf_classify net/sched/cls_api.c:1550 [inline]
 tcf_classify+0x218/0xad0 net/sched/cls_api.c:1616
 sch_handle_ingress net/core/dev.c:5199 [inline]
 __netif_receive_skb_core+0x1cd8/0x3670 net/core/dev.c:5412
 __netif_receive_skb_one_core net/core/dev.c:5549 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5665
 netif_receive_skb_internal net/core/dev.c:5751 [inline]
 netif_receive_skb+0x19e/0x700 net/core/dev.c:5810
 tun_rx_batched+0x606/0x760 drivers/net/tun.c:-1
 tun_get_user+0x2bf4/0x3b10 drivers/net/tun.c:2000
 tun_chr_write_iter+0x112/0x1e0 drivers/net/tun.c:2030
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7facf1bf4159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007facefe4c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007facf1e7bfa0 RCX: 00007facf1bf4159
RDX: 0000000000000fce RSI: 0000200000001280 RDI: 0000000000000003
RBP: 00007facf1c8b06b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007facf1e7c038 R14: 00007facf1e7bfa0 R15: 00007ffe4d4acd48
 </TASK>

Allocated by task 4532:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x92/0xc0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 kmem_cache_alloc_node+0x184/0x2c0 mm/slub.c:3261
 __alloc_skb+0xf4/0x750 net/core/skbuff.c:415
 alloc_skb include/linux/skbuff.h:1162 [inline]
 alloc_skb_with_frags+0xa7/0x720 net/core/skbuff.c:6199
 sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2535
 tun_alloc_skb drivers/net/tun.c:1515 [inline]
 tun_get_user+0x8f7/0x3b10 drivers/net/tun.c:1827
 tun_chr_write_iter+0x112/0x1e0 drivers/net/tun.c:2030
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 4532:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
 ____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1710 [inline]
 slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
 slab_free mm/slub.c:3504 [inline]
 kmem_cache_free+0x8f/0x210 mm/slub.c:3520
 kfree_skb include/linux/skbuff.h:1118 [inline]
 nf_ct_frag6_queue net/ipv6/netfilter/nf_conntrack_reasm.c:261 [inline]
 nf_ct_frag6_gather+0x1002/0x1da0 net/ipv6/netfilter/nf_conntrack_reasm.c:486
 tcf_ct_handle_fragments net/sched/act_ct.c:752 [inline]
 tcf_ct_act+0xc8d/0x3b40 net/sched/act_ct.c:1012
 tcf_action_exec+0x177/0x570 net/sched/act_api.c:761
 __tcf_classify net/sched/cls_api.c:1550 [inline]
 tcf_classify+0x218/0xad0 net/sched/cls_api.c:1616
 sch_handle_ingress net/core/dev.c:5199 [inline]
 __netif_receive_skb_core+0x1cd8/0x3670 net/core/dev.c:5412
 __netif_receive_skb_one_core net/core/dev.c:5549 [inline]
 __netif_receive_skb+0x74/0x290 net/core/dev.c:5665
 netif_receive_skb_internal net/core/dev.c:5751 [inline]
 netif_receive_skb+0x19e/0x700 net/core/dev.c:5810
 tun_rx_batched+0x606/0x760 drivers/net/tun.c:-1
 tun_get_user+0x2bf4/0x3b10 drivers/net/tun.c:2000
 tun_chr_write_iter+0x112/0x1e0 drivers/net/tun.c:2030
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff888023080a00
 which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 148 bytes inside of
 232-byte region [ffff888023080a00, ffff888023080ae8)
The buggy address belongs to the page:
page:ffffea00008c2000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x23080
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00017f7000 0000000900000002 ffff88801bbe4140
raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 3562, ts 27890453692, free_ts 27881804208
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x807/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 kmem_cache_alloc_node+0x118/0x2c0 mm/slub.c:3261
 __alloc_skb+0xf4/0x750 net/core/skbuff.c:415
 alloc_skb include/linux/skbuff.h:1162 [inline]
 alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:290
 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
 kobject_uevent_net_broadcast+0x2e6/0x530 lib/kobject_uevent.c:409
 kobject_uevent_env+0x550/0x890 lib/kobject_uevent.c:608
 kobject_synth_uevent+0x457/0x940 lib/kobject_uevent.c:208
 store_uevent+0x12/0x20 kernel/module.c:1167
 module_attr_store+0x5b/0x80 kernel/params.c:905
 kernfs_fop_write_iter+0x3a8/0x500 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2179 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x15d/0x280 mm/slub.c:3238
 getname_flags+0xb7/0x4f0 fs/namei.c:138
 do_sys_openat2+0xdd/0x500 fs/open.c:1249
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff888023080980: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
 ffff888023080a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888023080a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
                         ^
 ffff888023080b00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
 ffff888023080b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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