Kernel bug: KASAN: slab-use-after-free Read in __sk_msg_recvmsg
Subsystem: net, bpf
Status: open

Crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __sk_msg_recvmsg+0x91c/0xfc0 net/core/skmsg.c:454
Read of size 4 at addr ffff88802b37f828 by task syz.0.18/5832

CPU: 1 UID: 0 PID: 5832 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 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+0x91c/0xfc0 net/core/skmsg.c:454
 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: 0033:0x7fe29e99cdd9
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:00007fe29dfdd028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: ffffffffffffffda RBX: 00007fe29ec16090 RCX: 00007fe29e99cdd9
RDX: 0000000000000001 RSI: 0000200000000400 RDI: 0000000000000003
RBP: 00007fe29ea32d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000040000021 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe29ec16128 R14: 00007fe29ec16090 R15: 00007ffe2fa06638
 </TASK>

Allocated by task 5831:
 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:6245 [inline]
 __netif_receive_skb_list_core+0x7e5/0x810 net/core/dev.c:6292
 __netif_receive_skb_list net/core/dev.c:6344 [inline]
 netif_receive_skb_list_internal+0x995/0xcf0 net/core/dev.c:6435
 netif_receive_skb_list+0x55/0x450 net/core/dev.c:6487
 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 5833:
 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 ffff88802b37f800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 40 bytes inside of
 freed 1024-byte region [ffff88802b37f800, ffff88802b37fc00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2b378
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 ffff88813fe19dc0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe19dc0 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 5831, tgid 5830 (syz.0.18), ts 101787257274, free_ts 101782802143
 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]
 __kmalloc_cache_noprof+0x392/0x660 mm/slub.c:5410
 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
page last free pid 5831 tgid 5830 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
 bpf_check+0x3b1c/0x49f0 kernel/bpf/verifier.c:20201
 bpf_prog_load+0x1406/0x1a10 kernel/bpf/syscall.c:3082
 __sys_bpf+0x618/0x950 kernel/bpf/syscall.c:6248
 __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

Memory state around the buggy address:
 ffff88802b37f700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802b37f780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802b37f800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88802b37f880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802b37f900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================