Forwarded: Re: [syzbot] [usb?] general protection fault in f_midi2_stop_eps

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Subject: Re: [syzbot] [usb?] general protection fault in f_midi2_stop_eps
Author: pimyn@xxxxxxxxxx

#syz test


On Tue, Jul 28, 2026 at 3:41 PM syzbot
<syzbot+bbb6dad313f4aaa8da6b@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    3dab139d4795 Merge tag 'rust-fixes-7.2-2' of git://git.ker..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=137366b9580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cb17729fb04b1e3a
> dashboard link: https://syzkaller.appspot.com/bug?extid=bbb6dad313f4aaa8da6b
> compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1369b746580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=134a72ea580000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/647c579a2eab/disk-3dab139d.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/8800001c8ee2/vmlinux-3dab139d.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/337d386facb0/bzImage-3dab139d.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+bbb6dad313f4aaa8da6b@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> Oops: general protection fault, probably for non-canonical address 0xdffffc00000000ee: 0000 [#1] SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x0000000000000770-0x0000000000000777]
> CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
> RIP: 0010:f_midi2_free_ep_reqs drivers/usb/gadget/function/f_midi2.c:1166 [inline]
> RIP: 0010:f_midi2_stop_eps+0x28e/0x4d0 drivers/usb/gadget/function/f_midi2.c:1246
> Code: 89 f0 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 f7 e8 27 af e7 fa 41 bf 70 07 00 00 4d 03 3e 4c 89 f8 48 c1 e8 03 48 89 44 24 18 <42> 0f b6 04 28 84 c0 0f 85 12 02 00 00 41 8b 1f 31 ff 89 de e8 e9
> RSP: 0018:ffffc900001576f8 EFLAGS: 00010206
> RAX: 00000000000000ee RBX: ffff88802eae0120 RCX: ffff88801caa8000
> RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
> RBP: ffff88802eae0100 R08: ffffffff8faf9337 R09: 1ffffffff1f5f266
> R10: dffffc0000000000 R11: fffffbfff1f5f267 R12: ffff88802eae0770
> R13: dffffc0000000000 R14: ffff88802eae0128 R15: 0000000000000770
> FS:  0000000000000000(0000) GS:ffff888125c42000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055557b4714e8 CR3: 0000000035be2000 CR4: 00000000003526f0
> Call Trace:
>  <TASK>
>  f_midi2_set_alt+0x11c/0xf00 drivers/usb/gadget/function/f_midi2.c:1296
>  composite_setup+0x1ffd/0x3480 drivers/usb/gadget/composite.c:1933
>  configfs_composite_setup+0xbd/0x100 drivers/usb/gadget/configfs.c:1877
>  dummy_timer+0x2ea8/0x4b30 drivers/usb/gadget/udc/dummy_hcd.c:1937
>  __run_hrtimer kernel/time/hrtimer.c:2032 [inline]
>  __hrtimer_run_queues+0x3eb/0xaf0 kernel/time/hrtimer.c:2096
>  hrtimer_run_softirq+0x18f/0x260 kernel/time/hrtimer.c:2113
>  handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:622
>  __do_softirq kernel/softirq.c:656 [inline]
>  run_ktimerd+0x69/0x100 kernel/softirq.c:1151
>  smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
>  kthread+0x388/0x470 kernel/kthread.c:436
>  ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
>  </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:f_midi2_free_ep_reqs drivers/usb/gadget/function/f_midi2.c:1166 [inline]
> RIP: 0010:f_midi2_stop_eps+0x28e/0x4d0 drivers/usb/gadget/function/f_midi2.c:1246
> Code: 89 f0 48 c1 e8 03 42 80 3c 28 00 74 08 4c 89 f7 e8 27 af e7 fa 41 bf 70 07 00 00 4d 03 3e 4c 89 f8 48 c1 e8 03 48 89 44 24 18 <42> 0f b6 04 28 84 c0 0f 85 12 02 00 00 41 8b 1f 31 ff 89 de e8 e9
> RSP: 0018:ffffc900001576f8 EFLAGS: 00010206
> RAX: 00000000000000ee RBX: ffff88802eae0120 RCX: ffff88801caa8000
> RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
> RBP: ffff88802eae0100 R08: ffffffff8faf9337 R09: 1ffffffff1f5f266
> R10: dffffc0000000000 R11: fffffbfff1f5f267 R12: ffff88802eae0770
> R13: dffffc0000000000 R14: ffff88802eae0128 R15: 0000000000000770
> FS:  0000000000000000(0000) GS:ffff888125c42000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055557b4714e8 CR3: 0000000035be2000 CR4: 00000000003526f0
> ----------------
> Code disassembly (best guess):
>    0:   89 f0                   mov    %esi,%eax
>    2:   48 c1 e8 03             shr    $0x3,%rax
>    6:   42 80 3c 28 00          cmpb   $0x0,(%rax,%r13,1)
>    b:   74 08                   je     0x15
>    d:   4c 89 f7                mov    %r14,%rdi
>   10:   e8 27 af e7 fa          call   0xfae7af3c
>   15:   41 bf 70 07 00 00       mov    $0x770,%r15d
>   1b:   4d 03 3e                add    (%r14),%r15
>   1e:   4c 89 f8                mov    %r15,%rax
>   21:   48 c1 e8 03             shr    $0x3,%rax
>   25:   48 89 44 24 18          mov    %rax,0x18(%rsp)
> * 2a:   42 0f b6 04 28          movzbl (%rax,%r13,1),%eax <-- trapping instruction
>   2f:   84 c0                   test   %al,%al
>   31:   0f 85 12 02 00 00       jne    0x249
>   37:   41 8b 1f                mov    (%r15),%ebx
>   3a:   31 ff                   xor    %edi,%edi
>   3c:   89 de                   mov    %ebx,%esi
>   3e:   e8                      .byte 0xe8
>   3f:   e9                      .byte 0xe9
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>
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>
> If the report is already addressed, let syzbot know by replying with:
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>
> If you want syzbot to run the reproducer, reply with:
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>
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>
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>
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-- 
Ⲡⲟⲓⲙⲏⲛ Ⲅⲉⲱⲣⲅⲓⲟⲥ - Pimyn Girgis
Software Engineer
Kernel Dynamic Analysis
pimyn@xxxxxxxxxx