syzbot

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BUG: KASAN: use-after-free in __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1286 [inline]
BUG: KASAN: use-after-free in snd_rawmidi_transmit+0x392/0x400 sound/core/rawmidi.c:1411
Read of size 1 at addr ffff88806749c023 by task ksoftirqd/1/20

CPU: 1 PID: 20 Comm: ksoftirqd/1 Not tainted 5.15.186-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 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
 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1286 [inline]
 snd_rawmidi_transmit+0x392/0x400 sound/core/rawmidi.c:1411
 snd_usbmidi_standard_output+0x1e4/0xdd0 sound/usb/midi.c:718
 snd_usbmidi_do_output+0x21e/0x560 sound/usb/midi.c:311
 snd_usbmidi_error_timer+0x312/0x660 sound/usb/midi.c:362
 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
 expire_timers kernel/time/timer.c:1496 [inline]
 __run_timers+0x525/0x7c0 kernel/time/timer.c:1767
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
 handle_softirqs+0x328/0x820 kernel/softirq.c:576
 run_ksoftirqd+0x98/0xf0 kernel/softirq.c:943
 smpboot_thread_fn+0x4f6/0x970 kernel/smpboot.c:164
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Allocated by task 16242:
 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_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
 kmalloc_node include/linux/slab.h:627 [inline]
 kvmalloc_node+0x84/0x130 mm/util.c:619
 kvmalloc include/linux/mm.h:805 [inline]
 kvzalloc include/linux/mm.h:813 [inline]
 snd_rawmidi_runtime_create sound/core/rawmidi.c:162 [inline]
 open_substream+0x29d/0x6c0 sound/core/rawmidi.c:306
 rawmidi_open_priv+0xc4/0x660 sound/core/rawmidi.c:357
 snd_rawmidi_kernel_open+0x1a2/0x240 sound/core/rawmidi.c:392
 midisynth_use+0xd8/0x260 sound/core/seq/seq_midi.c:221
 subscribe_port sound/core/seq/seq_ports.c:412 [inline]
 check_and_subscribe_port+0x669/0xb30 sound/core/seq/seq_ports.c:495
 snd_seq_port_connect+0x256/0x430 sound/core/seq/seq_ports.c:581
 snd_seq_ioctl_subscribe_port+0x32c/0x6f0 sound/core/seq/seq_clientmgr.c:1490
 snd_seq_oss_midi_open+0x3a4/0x7c0 sound/core/seq/oss/seq_oss_midi.c:365
 snd_seq_oss_synth_setup_midi+0x129/0x520 sound/core/seq/oss/seq_oss_synth.c:269
 snd_seq_oss_open+0x87a/0xe40 sound/core/seq/oss/seq_oss_init.c:261
 odev_open+0x63/0x90 sound/core/seq/oss/seq_oss.c:128
 chrdev_open+0x597/0x670 fs/char_dev.c:414
 do_dentry_open+0x7ff/0xf80 fs/open.c:826
 do_open fs/namei.c:3608 [inline]
 path_openat+0x2682/0x2f30 fs/namei.c:3742
 do_filp_open+0x1b3/0x3e0 fs/namei.c:3769
 do_sys_openat2+0x142/0x4a0 fs/open.c:1253
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1280
 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 16242:
 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:1705 [inline]
 slab_free_freelist_hook+0xea/0x170 mm/slub.c:1731
 slab_free mm/slub.c:3499 [inline]
 kfree+0xef/0x2a0 mm/slub.c:4559
 snd_rawmidi_runtime_free sound/core/rawmidi.c:176 [inline]
 close_substream+0x360/0x5a0 sound/core/rawmidi.c:528
 rawmidi_release_priv+0xe9/0x170 sound/core/rawmidi.c:547
 snd_rawmidi_kernel_release+0x42/0xa0 sound/core/rawmidi.c:564
 unsubscribe_port sound/core/seq/seq_ports.c:437 [inline]
 __delete_and_unsubscribe_port+0x280/0x430 sound/core/seq/seq_ports.c:537
 snd_seq_port_disconnect+0x4f5/0x620 sound/core/seq/seq_ports.c:616
 snd_seq_ioctl_unsubscribe_port+0x32c/0x6f0 sound/core/seq/seq_clientmgr.c:1535
 snd_seq_oss_midi_close+0x2fc/0x620 sound/core/seq/oss/seq_oss_midi.c:413
 snd_seq_oss_synth_reset+0x3e9/0x960 sound/core/seq/oss/seq_oss_synth.c:406
 snd_seq_oss_reset+0x56/0x240 sound/core/seq/oss/seq_oss_init.c:436
 snd_seq_oss_release+0xe8/0x2c0 sound/core/seq/oss/seq_oss_init.c:413
 odev_release+0x52/0x70 sound/core/seq/oss/seq_oss.c:144
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88806749c000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 35 bytes inside of
 4096-byte region [ffff88806749c000, ffff88806749d000)
The buggy address belongs to the page:
page:ffffea00019d2600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x67498
head:ffffea00019d2600 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888016842140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 16242, ts 1011852404328, free_ts 1011353893123
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5474
 alloc_slab_page mm/slub.c:1775 [inline]
 allocate_slab mm/slub.c:1912 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1975
 ___slab_alloc+0x81e/0xdf0 mm/slub.c:3008
 __slab_alloc mm/slub.c:3095 [inline]
 slab_alloc_node mm/slub.c:3186 [inline]
 __kmalloc_node+0x200/0x3b0 mm/slub.c:4451
 kmalloc_node include/linux/slab.h:627 [inline]
 kvmalloc_node+0x84/0x130 mm/util.c:619
 kvmalloc include/linux/mm.h:805 [inline]
 kvzalloc include/linux/mm.h:813 [inline]
 snd_rawmidi_runtime_create sound/core/rawmidi.c:162 [inline]
 open_substream+0x29d/0x6c0 sound/core/rawmidi.c:306
 rawmidi_open_priv+0xc4/0x660 sound/core/rawmidi.c:357
 snd_rawmidi_kernel_open+0x1a2/0x240 sound/core/rawmidi.c:392
 midisynth_use+0xd8/0x260 sound/core/seq/seq_midi.c:221
 subscribe_port sound/core/seq/seq_ports.c:412 [inline]
 check_and_subscribe_port+0x669/0xb30 sound/core/seq/seq_ports.c:495
 snd_seq_port_connect+0x256/0x430 sound/core/seq/seq_ports.c:581
 snd_seq_ioctl_subscribe_port+0x32c/0x6f0 sound/core/seq/seq_clientmgr.c:1490
 snd_seq_oss_midi_open+0x3a4/0x7c0 sound/core/seq/oss/seq_oss_midi.c:365
 snd_seq_oss_synth_setup_midi+0x129/0x520 sound/core/seq/oss/seq_oss_synth.c:269
 snd_seq_oss_open+0x87a/0xe40 sound/core/seq/oss/seq_oss_init.c:261
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+0x94/0x280 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/0xd0 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:3220 [inline]
 slab_alloc mm/slub.c:3228 [inline]
 kmem_cache_alloc+0x100/0x290 mm/slub.c:3233
 getname_flags+0xb5/0x500 fs/namei.c:138
 do_sys_openat2+0xcf/0x4a0 fs/open.c:1247
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1280
 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:
 ffff88806749bf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88806749bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88806749c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88806749c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806749c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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