Hello, When fuzzing the Linux kernel driver v5.18.0, the following crash was triggered. HEAD commit: 4b0986a3613c92f4ec1bdc7f60ec66fea135991f git tree: upstream kernel config: https://pastebin.com/raw/KecL2gaG console output: https://pastebin.com/raw/aJGZYGs4 Sorry for failing to extract the reproducer. But on other versions of Linux, I also triggered this crash. I would appreciate it if you have any idea how to solve this bug. The crash report is as follows: ================================================================== BUG: KASAN: use-after-free in snd_rawmidi_receive+0x2f6/0xe70 sound/core/rawmidi.c:1097 Write of size 3 at addr ffff88803cf1a05a by task kworker/u8:6/13973 CPU: 3 PID: 13973 Comm: kworker/u8:6 Not tainted 5.18.0 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Workqueue: bat_events batadv_nc_worker Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:313 [inline] print_report.cold+0xe5/0x659 mm/kasan/report.c:429 kasan_report+0x8a/0x1b0 mm/kasan/report.c:491 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x13b/0x190 mm/kasan/generic.c:189 memcpy+0x39/0x60 mm/kasan/shadow.c:66 snd_rawmidi_receive+0x2f6/0xe70 sound/core/rawmidi.c:1097 f_midi_read_data drivers/usb/gadget/function/f_midi.c:253 [inline] f_midi_handle_out_data.isra.0+0x1ee/0x290 drivers/usb/gadget/function/f_midi.c:265 f_midi_complete+0x3b7/0x480 drivers/usb/gadget/function/f_midi.c:280 transfer drivers/usb/gadget/udc/dummy_hcd.c:1516 [inline] dummy_timer+0x1866/0x33b0 drivers/usb/gadget/udc/dummy_hcd.c:1972 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers kernel/time/timer.c:1737 [inline] __run_timers kernel/time/timer.c:1710 [inline] run_timer_softirq+0x1084/0x16d0 kernel/time/timer.c:1750 __do_softirq+0x1d0/0x908 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu kernel/softirq.c:637 [inline] irq_exit_rcu+0xf2/0x130 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:645 RIP: 0010:lock_release+0x3f0/0x670 kernel/locking/lockdep.c:5649 Code: 7e 83 f8 01 0f 85 59 01 00 00 9c 58 f6 c4 02 0f 85 44 01 00 00 48 f7 04 24 00 02 00 00 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c5 48 c7 45 00 00 00 00 00 c7 45 08 00 00 00 00 48 8b 84 24 RSP: 0018:ffffc90008a0fb90 EFLAGS: 00000206 RAX: dffffc0000000000 RBX: c422640388757846 RCX: 0000000000000000 RDX: 1ffff11007b1f892 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 1ffff92001141f74 R08: 0000000000000001 R09: fffffbfff1ce851b R10: ffffffff8e7428d7 R11: fffffbfff1ce851a R12: 0000000000000002 R13: ffff88803d8fc498 R14: 0000000000000003 R15: ffff88803d8fba80 rcu_lock_release include/linux/rcupdate.h:273 [inline] rcu_read_unlock include/linux/rcupdate.h:727 [inline] batadv_nc_process_nc_paths.part.0+0x235/0x3c0 net/batman-adv/network-coding.c:699 batadv_nc_process_nc_paths net/batman-adv/network-coding.c:679 [inline] batadv_nc_worker+0x54f/0x770 net/batman-adv/network-coding.c:728 process_one_work+0x9cc/0x1650 kernel/workqueue.c:2289 worker_thread+0x623/0x1070 kernel/workqueue.c:2436 kthread+0x2e9/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298 </TASK> Allocated by task 17441: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:436 [inline] ____kasan_kmalloc mm/kasan/common.c:515 [inline] ____kasan_kmalloc mm/kasan/common.c:474 [inline] __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524 kasan_kmalloc include/linux/kasan.h:234 [inline] __kmalloc_node+0x1fc/0x450 mm/slub.c:4462 kmalloc_node include/linux/slab.h:604 [inline] kvmalloc_node+0x3e/0x190 mm/util.c:580 kvmalloc include/linux/slab.h:731 [inline] kvzalloc include/linux/slab.h:739 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:162 [inline] open_substream+0x340/0x8b0 sound/core/rawmidi.c:306 rawmidi_open_priv+0x2e8/0x6f0 sound/core/rawmidi.c:352 snd_rawmidi_kernel_open+0x1b5/0x270 sound/core/rawmidi.c:392 midisynth_subscribe+0xf2/0x380 sound/core/seq/seq_midi.c:171 subscribe_port sound/core/seq/seq_ports.c:412 [inline] check_and_subscribe_port+0x5be/0x810 sound/core/seq/seq_ports.c:495 snd_seq_port_connect+0x2e6/0x520 sound/core/seq/seq_ports.c:576 snd_seq_ioctl_subscribe_port+0x1df/0x310 sound/core/seq/seq_clientmgr.c:1492 snd_seq_kernel_client_ctl+0x105/0x1b0 sound/core/seq/seq_clientmgr.c:2369 snd_seq_oss_midi_open+0x3f4/0x670 sound/core/seq/oss/seq_oss_midi.c:368 snd_seq_oss_synth_reset+0x462/0x890 sound/core/seq/oss/seq_oss_synth.c:407 snd_seq_oss_reset+0x6f/0x290 sound/core/seq/oss/seq_oss_init.c:435 snd_seq_oss_release+0x79/0x160 sound/core/seq/oss/seq_oss_init.c:412 odev_release+0x4f/0x70 sound/core/seq/oss/seq_oss.c:144 __fput+0x277/0x9d0 fs/file_table.c:317 task_work_run+0xe0/0x1a0 kernel/task_work.c:164 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:169 [inline] exit_to_user_mode_prepare+0x253/0x260 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:294 do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 17441: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0x11d/0x190 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1728 [inline] slab_free_freelist_hook mm/slub.c:1754 [inline] slab_free mm/slub.c:3510 [inline] kfree+0xec/0x4b0 mm/slub.c:4552 kvfree+0x42/0x50 mm/util.c:622 snd_rawmidi_runtime_free sound/core/rawmidi.c:176 [inline] close_substream.part.0+0x18e/0x650 sound/core/rawmidi.c:528 close_substream sound/core/rawmidi.c:507 [inline] rawmidi_release_priv+0xd3/0x270 sound/core/rawmidi.c:543 snd_rawmidi_kernel_release+0x39/0xd0 sound/core/rawmidi.c:564 midisynth_unsubscribe+0x3b/0x70 sound/core/seq/seq_midi.c:203 unsubscribe_port sound/core/seq/seq_ports.c:437 [inline] __delete_and_unsubscribe_port+0x279/0x4e0 sound/core/seq/seq_ports.c:537 delete_and_unsubscribe_port+0x59/0x80 sound/core/seq/seq_ports.c:549 snd_seq_port_disconnect+0x1ee/0x270 sound/core/seq/seq_ports.c:627 snd_seq_ioctl_unsubscribe_port+0x1df/0x310 sound/core/seq/seq_clientmgr.c:1537 snd_seq_kernel_client_ctl+0x105/0x1b0 sound/core/seq/seq_clientmgr.c:2369 snd_seq_oss_midi_close+0x2ff/0x470 sound/core/seq/oss/seq_oss_midi.c:410 snd_seq_oss_synth_cleanup+0x32c/0x480 sound/core/seq/oss/seq_oss_synth.c:307 snd_seq_oss_release+0x81/0x160 sound/core/seq/oss/seq_oss_init.c:414 odev_release+0x4f/0x70 sound/core/seq/oss/seq_oss.c:144 __fput+0x277/0x9d0 fs/file_table.c:317 task_work_run+0xe0/0x1a0 kernel/task_work.c:164 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:169 [inline] exit_to_user_mode_prepare+0x253/0x260 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:294 do_syscall_64+0x42/0x80 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88803cf1a000 which belongs to the cache kmalloc-4k of size 4096 The buggy address is located 90 bytes inside of 4096-byte region [ffff88803cf1a000, ffff88803cf1b000) The buggy address belongs to the physical page: page:ffffea0000f3c600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3cf18 head:ffffea0000f3c600 order:3 compound_mapcount:0 compound_pincount:0 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888011843040 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 17441, tgid 17441 (syz-executor.0), ts 589072773595, free_ts 589014752799 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2434 [inline] prep_new_page+0x297/0x330 mm/page_alloc.c:2441 get_page_from_freelist+0x210e/0x3ab0 mm/page_alloc.c:4182 __alloc_pages+0x30c/0x6e0 mm/page_alloc.c:5408 alloc_pages+0x119/0x250 mm/mempolicy.c:2272 alloc_slab_page mm/slub.c:1799 [inline] allocate_slab mm/slub.c:1944 [inline] new_slab+0x2a9/0x3f0 mm/slub.c:2004 ___slab_alloc+0xc62/0x1080 mm/slub.c:3005 __slab_alloc.isra.0+0x4d/0xa0 mm/slub.c:3092 slab_alloc_node mm/slub.c:3183 [inline] __kmalloc_node+0x340/0x450 mm/slub.c:4458 kmalloc_node include/linux/slab.h:604 [inline] kvmalloc_node+0x3e/0x190 mm/util.c:580 kvmalloc include/linux/slab.h:731 [inline] kvzalloc include/linux/slab.h:739 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:162 [inline] open_substream+0x340/0x8b0 sound/core/rawmidi.c:306 rawmidi_open_priv+0x592/0x6f0 sound/core/rawmidi.c:357 snd_rawmidi_kernel_open+0x1b5/0x270 sound/core/rawmidi.c:392 midisynth_use+0xee/0x270 sound/core/seq/seq_midi.c:215 subscribe_port sound/core/seq/seq_ports.c:412 [inline] check_and_subscribe_port+0x5be/0x810 sound/core/seq/seq_ports.c:495 snd_seq_port_connect+0x382/0x520 sound/core/seq/seq_ports.c:581 snd_seq_ioctl_subscribe_port+0x1df/0x310 sound/core/seq/seq_clientmgr.c:1492 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1356 [inline] free_pcp_prepare+0x51f/0xd00 mm/page_alloc.c:1406 free_unref_page_prepare mm/page_alloc.c:3328 [inline] free_unref_page+0x19/0x5b0 mm/page_alloc.c:3423 __unfreeze_partials+0x3d2/0x3f0 mm/slub.c:2523 do_slab_free mm/slub.c:3498 [inline] ___cache_free+0x12c/0x140 mm/slub.c:3517 qlink_free mm/kasan/quarantine.c:157 [inline] qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:176 kasan_quarantine_reduce+0x13d/0x180 mm/kasan/quarantine.c:283 __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:446 kasan_slab_alloc include/linux/kasan.h:224 [inline] slab_post_alloc_hook+0x4d/0x4f0 mm/slab.h:749 slab_alloc_node mm/slub.c:3217 [inline] slab_alloc mm/slub.c:3225 [inline] __kmem_cache_alloc_lru mm/slub.c:3232 [inline] kmem_cache_alloc+0x1be/0x460 mm/slub.c:3242 getname_flags fs/namei.c:138 [inline] getname_flags+0xd2/0x5b0 fs/namei.c:128 vfs_fstatat+0x73/0xb0 fs/stat.c:254 __do_sys_newfstatat+0x91/0x110 fs/stat.c:425 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Memory state around the buggy address: ffff88803cf19f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88803cf19f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88803cf1a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88803cf1a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88803cf1a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ---------------- Code disassembly (best guess): 0: 7e 83 jle 0xffffff85 2: f8 clc 3: 01 0f add %ecx,(%rdi) 5: 85 59 01 test %ebx,0x1(%rcx) 8: 00 00 add %al,(%rax) a: 9c pushfq b: 58 pop %rax c: f6 c4 02 test $0x2,%ah f: 0f 85 44 01 00 00 jne 0x159 15: 48 f7 04 24 00 02 00 testq $0x200,(%rsp) 1c: 00 1d: 74 01 je 0x20 1f: fb sti 20: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 27: fc ff df * 2a: 48 01 c5 add %rax,%rbp <-- trapping instruction 2d: 48 c7 45 00 00 00 00 movq $0x0,0x0(%rbp) 34: 00 35: c7 45 08 00 00 00 00 movl $0x0,0x8(%rbp) 3c: 48 rex.W 3d: 8b .byte 0x8b 3e: 84 .byte 0x84 3f: 24 .byte 0x24
