================================================================== BUG: KASAN: slab-use-after-free in __sk_msg_recvmsg+0x81c/0xe70 net/core/skmsg.c:454 Read of size 4 at addr ffff888033a25028 by task syz.0.18/6018 CPU: 0 UID: 0 PID: 6018 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xba/0x230 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 __sk_msg_recvmsg+0x81c/0xe70 net/core/skmsg.c:454 udp_bpf_recvmsg+0x196/0xac0 net/ipv4/udp_bpf.c:83 sock_recvmsg_nosec net/socket.c:1071 [inline] sock_recvmsg+0x155/0x1b0 net/socket.c:1093 ____sys_recvmsg+0x1e6/0x4a0 net/socket.c:2805 ___sys_recvmsg+0x215/0x590 net/socket.c:2847 do_recvmmsg+0x334/0x800 net/socket.c:2942 __sys_recvmmsg net/socket.c:3016 [inline] __do_sys_recvmmsg net/socket.c:3039 [inline] __se_sys_recvmmsg net/socket.c:3032 [inline] __x64_sys_recvmmsg+0x198/0x250 net/socket.c:3032 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fcf84f9c799 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:00007fcf85f1c028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007fcf85216090 RCX: 00007fcf84f9c799 RDX: 0000000000000001 RSI: 0000200000000400 RDI: 0000000000000003 RBP: 00007fcf85032c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000040000021 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fcf85216128 R14: 00007fcf85216090 R15: 00007ffd20c297b8 Allocated by task 6017: 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:5380 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:2033 sk_psock_verdict_data_ready+0x12d/0x590 net/core/skmsg.c:1281 __udp_enqueue_schedule_skb+0xc4b/0x12e0 net/ipv4/udp.c:1760 __udp_queue_rcv_skb net/ipv4/udp.c:2335 [inline] udp_queue_rcv_one_skb+0x831/0x1230 net/ipv4/udp.c:2425 __udp4_lib_mcast_deliver+0xad7/0xb70 net/ipv4/udp.c:2538 udp_rcv+0xcc2/0x24c0 net/ipv4/udp.c:2663 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:6224 [inline] __netif_receive_skb_list_core+0x7e5/0x810 net/core/dev.c:6271 __netif_receive_skb_list net/core/dev.c:6323 [inline] netif_receive_skb_list_internal+0x995/0xcf0 net/core/dev.c:6414 netif_receive_skb_list+0x55/0x4b0 net/core/dev.c:6466 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:1397 bpf_prog_test_run+0x2c7/0x340 kernel/bpf/syscall.c:4722 __sys_bpf+0x643/0x950 kernel/bpf/syscall.c:6246 __do_sys_bpf kernel/bpf/syscall.c:6341 [inline] __se_sys_bpf kernel/bpf/syscall.c:6339 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6339 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6019: 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:2685 [inline] slab_free mm/slub.c:6165 [inline] kfree+0x1c1/0x630 mm/slub.c:6483 kfree_sk_msg include/linux/skmsg.h:418 [inline] __sk_msg_recvmsg+0xc7e/0xe70 net/core/skmsg.c:491 udp_bpf_recvmsg+0x196/0xac0 net/ipv4/udp_bpf.c:83 sock_recvmsg_nosec net/socket.c:1071 [inline] sock_recvmsg+0x155/0x1b0 net/socket.c:1093 ____sys_recvmsg+0x1e6/0x4a0 net/socket.c:2805 ___sys_recvmsg+0x215/0x590 net/socket.c:2847 do_recvmmsg+0x334/0x800 net/socket.c:2942 __sys_recvmmsg net/socket.c:3016 [inline] __do_sys_recvmmsg net/socket.c:3039 [inline] __se_sys_recvmmsg net/socket.c:3032 [inline] __x64_sys_recvmmsg+0x198/0x250 net/socket.c:3032 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888033a25000 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 40 bytes inside of freed 1024-byte region [ffff888033a25000, ffff888033a25400) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33a20 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 ffff88813fea8dc0 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88813fea8dc0 dead000000000100 dead000000000122 head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 head: 00fff00000000003 ffffea0000ce8801 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5712, tgid 5712 (dhcpcd), ts 66229079291, free_ts 65113534748 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889 prep_new_page mm/page_alloc.c:1897 [inline] get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250 alloc_slab_page mm/slub.c:3292 [inline] allocate_slab+0x77/0x660 mm/slub.c:3481 new_slab mm/slub.c:3539 [inline] refill_objects+0x331/0x3c0 mm/slub.c:7175 refill_sheaf mm/slub.c:2812 [inline] __pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615 alloc_from_pcs mm/slub.c:4717 [inline] slab_alloc_node mm/slub.c:4851 [inline] __do_kmalloc_node mm/slub.c:5259 [inline] __kmalloc_noprof+0x474/0x760 mm/slub.c:5272 kmalloc_noprof include/linux/slab.h:954 [inline] load_elf_phdrs fs/binfmt_elf.c:541 [inline] load_elf_binary+0x30f/0x2980 fs/binfmt_elf.c:870 search_binary_handler fs/exec.c:1664 [inline] exec_binprm fs/exec.c:1696 [inline] bprm_execve+0x93d/0x1460 fs/exec.c:1748 do_execveat_common+0x50d/0x690 fs/exec.c:1846 __do_sys_execve fs/exec.c:1930 [inline] __se_sys_execve fs/exec.c:1924 [inline] __x64_sys_execve+0x97/0xc0 fs/exec.c:1924 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5489 tgid 5489 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1433 [inline] __free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978 __slab_free+0x263/0x2b0 mm/slub.c:5573 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x97/0x100 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:4538 [inline] slab_alloc_node mm/slub.c:4866 [inline] kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4918 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 alloc_skb include/linux/skbuff.h:1383 [inline] alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6752 sock_alloc_send_pskb+0x878/0x990 net/core/sock.c:2995 unix_dgram_sendmsg+0x460/0x18e0 net/unix/af_unix.c:2127 sock_sendmsg_nosec net/socket.c:721 [inline] __sock_sendmsg net/socket.c:736 [inline] sock_write_iter+0x49b/0x4f0 net/socket.c:1188 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x61d/0xb90 fs/read_write.c:688 ksys_write+0x150/0x270 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888033a24f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888033a24f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888033a25000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888033a25080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888033a25100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================