================================================================== BUG: KASAN: slab-use-after-free in __sk_msg_recvmsg+0x197/0xfc0 net/core/skmsg.c:431 Read of size 8 at addr ffff88807a4ee2b0 by task syz.0.33/6124 CPU: 1 UID: 0 PID: 6124 Comm: syz.0.33 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 __sk_msg_recvmsg+0x197/0xfc0 net/core/skmsg.c:431 udp_bpf_recvmsg+0x196/0xac0 net/ipv4/udp_bpf.c:83 sock_recvmsg_nosec net/socket.c:1137 [inline] sock_recvmsg+0x155/0x1b0 net/socket.c:1159 ____sys_recvmsg+0x1e6/0x4a0 net/socket.c:2918 ___sys_recvmsg+0x215/0x590 net/socket.c:2960 do_recvmmsg+0x334/0x800 net/socket.c:3055 __sys_recvmmsg net/socket.c:3129 [inline] __do_sys_recvmmsg net/socket.c:3152 [inline] __se_sys_recvmmsg net/socket.c:3145 [inline] __x64_sys_recvmmsg+0x198/0x250 net/socket.c:3145 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f001db9cdd9 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:00007f001ea09028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007f001de16180 RCX: 00007f001db9cdd9 RDX: 0000000000000012 RSI: 0000200000000400 RDI: 0000000000000003 RBP: 00007f001dc32d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000040000021 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f001de16218 R14: 00007f001de16180 R15: 00007ffc4668cb68 Allocated by task 6122: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5415 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] alloc_sk_msg net/core/skmsg.c:525 [inline] sk_psock_skb_ingress_self+0x5e/0x370 net/core/skmsg.c:627 sk_psock_verdict_apply net/core/skmsg.c:1062 [inline] sk_psock_verdict_recv+0x7d9/0x8d0 net/core/skmsg.c:1260 udp_read_skb+0x5d9/0x6b0 net/ipv4/udp.c:2014 sk_psock_verdict_data_ready+0x25f/0x690 net/core/skmsg.c:1284 __udp_enqueue_schedule_skb+0xc4b/0x12e0 net/ipv4/udp.c:1745 __udp_queue_rcv_skb net/ipv4/udp.c:2311 [inline] udp_queue_rcv_one_skb+0x755/0x10f0 net/ipv4/udp.c:2402 __udp4_lib_mcast_deliver+0xad7/0xb70 net/ipv4/udp.c:2514 udp_rcv+0xcd0/0x1db0 net/ipv4/udp.c:2639 ip_protocol_deliver_rcu+0x282/0x440 net/ipv4/ip_input.c:207 ip_local_deliver_finish+0x3bb/0x6f0 net/ipv4/ip_input.c:241 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 dst_input include/net/dst.h:480 [inline] ip_sublist_rcv_finish+0x1f0/0x240 net/ipv4/ip_input.c:623 ip_list_rcv_finish net/ipv4/ip_input.c:667 [inline] ip_sublist_rcv+0x5c6/0xa70 net/ipv4/ip_input.c:683 ip_list_rcv+0x3f1/0x450 net/ipv4/ip_input.c:717 __netif_receive_skb_list_ptype net/core/dev.c:6252 [inline] __netif_receive_skb_list_core+0x7e5/0x810 net/core/dev.c:6299 __netif_receive_skb_list net/core/dev.c:6351 [inline] netif_receive_skb_list_internal+0x995/0xcf0 net/core/dev.c:6442 netif_receive_skb_list+0x55/0x450 net/core/dev.c:6494 xdp_recv_frames net/bpf/test_run.c:269 [inline] xdp_test_run_batch net/bpf/test_run.c:350 [inline] bpf_test_run_xdp_live+0x1946/0x1cf0 net/bpf/test_run.c:379 bpf_prog_test_run_xdp+0x81c/0x1160 net/bpf/test_run.c:1430 bpf_prog_test_run+0x2c7/0x340 kernel/bpf/syscall.c:4742 __sys_bpf+0x643/0x950 kernel/bpf/syscall.c:6266 __do_sys_bpf kernel/bpf/syscall.c:6361 [inline] __se_sys_bpf kernel/bpf/syscall.c:6359 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6359 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6123: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6246 [inline] kfree+0x1c5/0x640 mm/slub.c:6561 kfree_sk_msg include/linux/skmsg.h:418 [inline] __sk_msg_recvmsg+0xdb7/0xfc0 net/core/skmsg.c:491 udp_bpf_recvmsg+0x196/0xac0 net/ipv4/udp_bpf.c:83 sock_recvmsg_nosec net/socket.c:1137 [inline] sock_recvmsg+0x155/0x1b0 net/socket.c:1159 ____sys_recvmsg+0x1e6/0x4a0 net/socket.c:2918 ___sys_recvmsg+0x215/0x590 net/socket.c:2960 do_recvmmsg+0x334/0x800 net/socket.c:3055 __sys_recvmmsg net/socket.c:3129 [inline] __do_sys_recvmmsg net/socket.c:3152 [inline] __se_sys_recvmmsg net/socket.c:3145 [inline] __x64_sys_recvmmsg+0x198/0x250 net/socket.c:3145 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88807a4ee000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 688 bytes inside of freed 1024-byte region [ffff88807a4ee000, ffff88807a4ee400) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7a4e8 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88813fe2edc0 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fe2edc0 dead000000000100 dead000000000122 head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5873, tgid 5873 (kworker/1:4), ts 74024369884, free_ts 73958339825 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858 prep_new_page mm/page_alloc.c:1866 [inline] get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226 alloc_slab_page mm/slub.c:3278 [inline] allocate_slab+0x77/0x660 mm/slub.c:3467 new_slab mm/slub.c:3525 [inline] refill_objects+0x339/0x3d0 mm/slub.c:7251 refill_sheaf mm/slub.c:2816 [inline] __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4651 alloc_from_pcs mm/slub.c:4749 [inline] slab_alloc_node mm/slub.c:4883 [inline] __do_kmalloc_node mm/slub.c:5294 [inline] __kmalloc_noprof+0x474/0x760 mm/slub.c:5307 kmalloc_noprof include/linux/slab.h:954 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] neigh_alloc net/core/neighbour.c:521 [inline] ___neigh_create+0x6d5/0x2250 net/core/neighbour.c:655 ip6_finish_output2+0x729/0x13e0 net/ipv6/ip6_output.c:128 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:246 dst_output include/net/dst.h:470 [inline] NF_HOOK+0x177/0x4f0 include/linux/netfilter.h:318 mld_sendpack+0x8b4/0xe40 net/ipv6/mcast.c:1855 mld_send_cr net/ipv6/mcast.c:2154 [inline] mld_ifc_work+0x835/0xe70 net/ipv6/mcast.c:2693 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466 kthread+0x388/0x470 kernel/kthread.c:436 page last free pid 24 tgid 24 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1402 [inline] __free_frozen_pages+0xbc7/0xd30 mm/page_alloc.c:2943 __slab_free+0x274/0x2c0 mm/slub.c:5608 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4569 [inline] slab_alloc_node mm/slub.c:4898 [inline] kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4950 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 alloc_skb include/linux/skbuff.h:1383 [inline] mld_newpack+0x14c/0xc90 net/ipv6/mcast.c:1775 add_grhead+0x5a/0x2a0 net/ipv6/mcast.c:1886 add_grec+0x1452/0x1740 net/ipv6/mcast.c:2025 mld_send_cr net/ipv6/mcast.c:2148 [inline] mld_ifc_work+0x6e6/0xe70 net/ipv6/mcast.c:2693 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Memory state around the buggy address: ffff88807a4ee180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807a4ee200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88807a4ee280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807a4ee300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807a4ee380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================