syzbot

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BUG: KASA[  995.576952][T10614] BUG: KASAN: slab-use-after-free in rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56
Read of size 1 at addr ffff88801fbe8200 by task syz.2.974/10614

CPU: 0 UID: 0 PID: 10614 Comm: syz.2.974 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 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
 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:574
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire+0x84/0x330 kernel/locking/lockdep.c:5842
 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 __wake_up_common_lock+0x2f/0x1e0 kernel/sched/wait.c:124
 snd_pcm_action_single sound/core/pcm_native.c:-1 [inline]
 snd_pcm_action+0x1f4/0x240 sound/core/pcm_native.c:1398
 loopback_check_format sound/drivers/aloop.c:363 [inline]
 loopback_trigger+0xb82/0x1b60 sound/drivers/aloop.c:411
 snd_pcm_do_start+0xb7/0x180 sound/core/pcm_native.c:1459
 snd_pcm_action_single sound/core/pcm_native.c:1315 [inline]
 snd_pcm_action+0xe7/0x240 sound/core/pcm_native.c:1398
 __snd_pcm_lib_xfer+0x175a/0x1d10 sound/core/pcm_lib.c:2405
 snd_pcm_oss_write3+0x1bc/0x350 sound/core/oss/pcm_oss.c:1243
 snd_pcm_plug_write_transfer+0x2d1/0x4d0 sound/core/oss/pcm_plugin.c:630
 snd_pcm_oss_write2+0x283/0x440 sound/core/oss/pcm_oss.c:1375
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1441 [inline]
 snd_pcm_oss_write+0x579/0x940 sound/core/oss/pcm_oss.c:2796
 vfs_write+0x2a3/0xba0 fs/read_write.c:684
 ksys_write+0x156/0x270 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f986529acb9
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:00007f98634b4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9865516180 RCX: 00007f986529acb9
RDX: 0000000000004000 RSI: 00002000000012c0 RDI: 0000000000000007
RBP: 00007f9865308bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9865516218 R14: 00007f9865516180 R15: 00007fff60498318
 </TASK>

Allocated by task 10613:
 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+0x1f2/0x6b0 mm/slub.c:5780
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 snd_pcm_attach_substream+0x5b7/0xb20 sound/core/pcm.c:938
 snd_pcm_open_substream+0xbd/0x2420 sound/core/pcm_native.c:2761
 snd_pcm_oss_open_file sound/core/oss/pcm_oss.c:2439 [inline]
 snd_pcm_oss_open+0xfc2/0x1c50 sound/core/oss/pcm_oss.c:2520
 chrdev_open+0x4d0/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7d0/0x1270 fs/open.c:962
 vfs_open+0x3b/0x350 fs/open.c:1094
 do_open fs/namei.c:4637 [inline]
 path_openat+0x34c9/0x3e70 fs/namei.c:4796
 do_filp_open+0x22d/0x490 fs/namei.c:4823
 do_sys_openat2+0x12f/0x220 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 10611:
 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:2540 [inline]
 slab_free mm/slub.c:6674 [inline]
 kfree+0x1bb/0x8f0 mm/slub.c:6882
 snd_pcm_detach_substream+0x1e1/0x290 sound/core/pcm.c:1003
 snd_pcm_oss_release_file sound/core/oss/pcm_oss.c:2398 [inline]
 snd_pcm_oss_release+0x184/0x250 sound/core/oss/pcm_oss.c:2577
 __fput+0x45e/0xa80 fs/file_table.c:468
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x2b7/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88801fbe8000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 512 bytes inside of
 freed 2048-byte region [ffff88801fbe8000, ffff88801fbe8800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1fbe8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88813fea7000 ffffea0000d0e600 0000000000000002
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88813fea7000 ffffea0000d0e600 0000000000000002
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 0080000000000003 ffffea00007efa01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 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 10412, tgid 10404 (syz.0.928), ts 957459019447, free_ts 933763739397
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3945
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5240
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2486
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab+0x86/0x3a0 mm/slub.c:3248
 new_slab mm/slub.c:3302 [inline]
 ___slab_alloc+0xaf8/0x13d0 mm/slub.c:4656
 __slab_alloc+0xc5/0x1f0 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_node_track_caller_noprof+0x2b6/0x7f0 mm/slub.c:5768
 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:608
 __alloc_skb+0x204/0x390 net/core/skbuff.c:690
 alloc_skb include/linux/skbuff.h:1383 [inline]
 _sctp_make_chunk+0x59/0x290 net/sctp/sm_make_chunk.c:1435
 sctp_make_data net/sctp/sm_make_chunk.c:1467 [inline]
 sctp_make_datafrag_empty+0x12a/0x240 net/sctp/sm_make_chunk.c:732
 sctp_datamsg_from_user+0x729/0xef0 net/sctp/chunk.c:263
 sctp_sendmsg_to_asoc+0x1416/0x1900 net/sctp/socket.c:1858
 sctp_sendmsg+0x1768/0x2620 net/sctp/socket.c:2030
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x19c/0x270 net/socket.c:742
page last free pid 10182 tgid 10182 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xfc1/0x1130 mm/page_alloc.c:2973
 discard_slab mm/slub.c:3346 [inline]
 __put_partials+0x149/0x170 mm/slub.c:3886
 __slab_free+0x2af/0x330 mm/slub.c:5956
 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:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 __kmalloc_cache_noprof+0x188/0x6b0 mm/slub.c:5775
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 kset_create lib/kobject.c:965 [inline]
 kset_create_and_add+0x5a/0x180 lib/kobject.c:1008
 register_queue_kobjects net/core/net-sysfs.c:2106 [inline]
 netdev_register_kobject+0x1a2/0x310 net/core/net-sysfs.c:2362
 register_netdevice+0x1272/0x1ab0 net/core/dev.c:11406
 ipcaif_newlink+0x1fc/0x4e0 net/caif/chnl_net.c:452
 rtnl_newlink_create+0x329/0xb70 net/core/rtnetlink.c:3840
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0x1666/0x1be0 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x831/0x9f0 net/netlink/af_netlink.c:1344

Memory state around the buggy address:
 ffff88801fbe8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801fbe8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88801fbe8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88801fbe8280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801fbe8300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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