Hello, syzbot found the following crash on: HEAD commit: 0dc589da Merge tag 'iommu-fixes-v5.8-rc5' of git://git.ker.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1462e8e7100000 kernel config: https://syzkaller.appspot.com/x/.config?x=a160d1053fc89af5 dashboard link: https://syzkaller.appspot.com/bug?extid=7700c25812eaa5e88c8c compiler: gcc (GCC) 10.1.0-syz 20200507 Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+7700c25812eaa5e88c8c@xxxxxxxxxxxxxxxxxxxxxxxxx raw-gadget gadget: fail, usb_ep_enable returned -22 raw-gadget gadget: fail, usb_ep_enable returned -22 list_add double add: new=ffff88808f208718, prev=ffff88808f208718, next=ffff8880a6601a68. ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:29! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 441 Comm: syz-executor.4 Not tainted 5.8.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__list_add_valid.cold+0x26/0x3c lib/list_debug.c:29 Code: 57 ff ff ff 4c 89 e1 48 c7 c7 e0 90 93 88 e8 c1 06 c2 fd 0f 0b 48 89 f2 4c 89 e1 48 89 ee 48 c7 c7 20 92 93 88 e8 aa 06 c2 fd <0f> 0b 48 89 f1 48 c7 c7 a0 91 93 88 4c 89 e6 e8 96 06 c2 fd 0f 0b RSP: 0018:ffffc9000846f068 EFLAGS: 00010086 RAX: 0000000000000058 RBX: ffff88808f208700 RCX: 0000000000000000 RDX: 0000000000040000 RSI: ffffffff815d4f87 RDI: fffff5200108ddff RBP: ffff88808f208718 R08: 0000000000000058 R09: ffff8880ae6318e7 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a6601a68 R13: ffff88808f208718 R14: 0000000000000000 R15: ffff88808f208718 FS: 00007f08cc521700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056495a9c9848 CR3: 000000009ef59000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __list_add include/linux/list.h:67 [inline] list_add_tail include/linux/list.h:100 [inline] usb_hcd_link_urb_to_ep+0x21d/0x390 drivers/usb/core/hcd.c:1173 dummy_urb_enqueue+0x28e/0x890 drivers/usb/gadget/udc/dummy_hcd.c:1266 usb_hcd_submit_urb+0x2ad/0x2220 drivers/usb/core/hcd.c:1547 usb_submit_urb+0xb4e/0x1320 drivers/usb/core/urb.c:570 snd_usbmidi_submit_urb sound/usb/midi.c:194 [inline] snd_usbmidi_input_start_ep sound/usb/midi.c:2313 [inline] snd_usbmidi_input_start.part.0+0x101/0x200 sound/usb/midi.c:2329 snd_usbmidi_input_start sound/usb/midi.c:1119 [inline] substream_open.isra.0+0x82c/0xc10 sound/usb/midi.c:1119 open_substream+0x42e/0x880 sound/core/rawmidi.c:299 rawmidi_open_priv+0x519/0x6f0 sound/core/rawmidi.c:342 snd_rawmidi_kernel_open+0x1b5/0x270 sound/core/rawmidi.c:382 midisynth_subscribe+0xf2/0x350 sound/core/seq/seq_midi.c:170 subscribe_port sound/core/seq/seq_ports.c:412 [inline] check_and_subscribe_port+0x89a/0xb80 sound/core/seq/seq_ports.c:495 snd_seq_port_connect+0x2e6/0x520 sound/core/seq/seq_ports.c:564 snd_seq_ioctl_subscribe_port+0x1fc/0x400 sound/core/seq/seq_clientmgr.c:1484 snd_seq_kernel_client_ctl+0xeb/0x130 sound/core/seq/seq_clientmgr.c:2353 snd_seq_oss_midi_open+0x466/0x6e0 sound/core/seq/oss/seq_oss_midi.c:364 snd_seq_oss_synth_setup_midi+0x123/0x520 sound/core/seq/oss/seq_oss_synth.c:269 snd_seq_oss_open+0x87e/0xa10 sound/core/seq/oss/seq_oss_init.c:261 odev_open+0x6c/0x90 sound/core/seq/oss/seq_oss.c:125 soundcore_open+0x445/0x600 sound/sound_core.c:593 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x501/0x1290 fs/open.c:828 do_open fs/namei.c:3243 [inline] path_openat+0x1bb9/0x2750 fs/namei.c:3360 do_filp_open+0x17e/0x3c0 fs/namei.c:3387 do_sys_openat2+0x16f/0x3b0 fs/open.c:1179 do_sys_open fs/open.c:1195 [inline] __do_sys_openat fs/open.c:1209 [inline] __se_sys_openat fs/open.c:1204 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1204 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45cba9 Code: Bad RIP value. RSP: 002b:00007f08cc520c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00000000004fa1c0 RCX: 000000000045cba9 RDX: 0000000000000000 RSI: 0000000020000000 RDI: ffffffffffffff9c RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000813 R14: 00000000004caf66 R15: 00007f08cc5216d4 Modules linked in: ---[ end trace 514bb0012877d727 ]--- RIP: 0010:__list_add_valid.cold+0x26/0x3c lib/list_debug.c:29 Code: 57 ff ff ff 4c 89 e1 48 c7 c7 e0 90 93 88 e8 c1 06 c2 fd 0f 0b 48 89 f2 4c 89 e1 48 89 ee 48 c7 c7 20 92 93 88 e8 aa 06 c2 fd <0f> 0b 48 89 f1 48 c7 c7 a0 91 93 88 4c 89 e6 e8 96 06 c2 fd 0f 0b RSP: 0018:ffffc9000846f068 EFLAGS: 00010086 RAX: 0000000000000058 RBX: ffff88808f208700 RCX: 0000000000000000 RDX: 0000000000040000 RSI: ffffffff815d4f87 RDI: fffff5200108ddff RBP: ffff88808f208718 R08: 0000000000000058 R09: ffff8880ae6318e7 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a6601a68 R13: ffff88808f208718 R14: 0000000000000000 R15: ffff88808f208718 FS: 00007f08cc521700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056495a9c9848 CR3: 000000009ef59000 CR4: 00000000001426f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 --- This bug is generated by a bot. 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