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SMTP id 5614622812f47-4af5e1d3954mr3572758b6e.10.1785545122542; Fri, 31 Jul 2026 17:45:22 -0700 (PDT) Date: Fri, 31 Jul 2026 17:45:22 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a6d41a2.f794c993.27aeb.000c.GAE@google.com> Subject: [syzbot] [usb?] general protection fault in mon_notify From: syzbot To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 62cc90241548 Merge tag 'mm-hotfixes-stable-2026-07-27-14-1.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=156affde580000 kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782 dashboard link: https://syzkaller.appspot.com/bug?extid=5f4b29d9fe710a964482 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=131be449580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1467e499580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-62cc9024.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/b10a9ae7e3d1/vmlinux-62cc9024.xz kernel image: https://storage.googleapis.com/syzbot-assets/b89124d39495/bzImage-62cc9024.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+5f4b29d9fe710a964482@syzkaller.appspotmail.com dummy_hcd dummy_hcd.0: remove, state 4 usb usb5: USB disconnect, device number 1 dummy_hcd dummy_hcd.0: stopped dummy_hcd dummy_hcd.0: USB bus 5 deregistered Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 UID: 0 PID: 5954 Comm: syz.0.42 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__list_del_entry_valid_or_report+0x20/0x1d0 lib/list_debug.c:49 Code: 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 b8 00 00 00 00 00 fc ff df 41 54 55 53 48 89 fb 48 83 c7 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 5b 01 00 00 48 89 da 48 8b 6b 08 48 b8 00 00 00 RSP: 0018:ffffc9000374fa20 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: fffff520006e9f22 RDX: 0000000000000001 RSI: ffffffff8c401500 RDI: 0000000000000008 RBP: ffff88802ff87000 R08: 0000000000000000 R09: fffffbfff2244efa R10: ffffc9000374fa40 R11: 0000000000000000 R12: 00000000fffffffe R13: ffff88802ff870e8 R14: 0000000000000008 R15: 0000000000000000 FS: 000055556cf07500(0000) GS:ffff8880d5ddc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc48295da08 CR3: 000000003cd5d000 CR4: 0000000000352ef0 Call Trace: __list_del_entry_valid include/linux/list.h:132 [inline] __list_del_entry include/linux/list.h:246 [inline] list_del include/linux/list.h:260 [inline] mon_bus_remove drivers/usb/mon/mon_main.c:203 [inline] mon_notify+0x84/0x480 drivers/usb/mon/mon_main.c:222 notifier_call_chain+0x99/0x3f0 kernel/notifier.c:85 blocking_notifier_call_chain kernel/notifier.c:380 [inline] blocking_notifier_call_chain+0x69/0xa0 kernel/notifier.c:368 usb_remove_hcd.cold+0x25f/0x401 drivers/usb/core/hcd.c:3084 dummy_hcd_remove+0x109/0x1e0 drivers/usb/gadget/udc/dummy_hcd.c:2761 platform_remove+0x5f/0x80 drivers/base/platform.c:1456 device_remove+0xcb/0x180 drivers/base/dd.c:616 __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372 unbind_store+0xf8/0x110 drivers/base/bus.c:244 drv_attr_store+0x74/0xb0 drivers/base/bus.c:125 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc481b9de99 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:00007ffd993809e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fc481e25fa0 RCX: 00007fc481b9de99 RDX: 000000000000000b RSI: 0000200000000200 RDI: 0000000000000003 RBP: 00007fc481c33eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc481e25fac R14: 00007fc481e25fa0 R15: 00007fc481e25fa0 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:__list_del_entry_valid_or_report+0x20/0x1d0 lib/list_debug.c:49 Code: 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 b8 00 00 00 00 00 fc ff df 41 54 55 53 48 89 fb 48 83 c7 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 5b 01 00 00 48 89 da 48 8b 6b 08 48 b8 00 00 00 RSP: 0018:ffffc9000374fa20 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: fffff520006e9f22 RDX: 0000000000000001 RSI: ffffffff8c401500 RDI: 0000000000000008 RBP: ffff88802ff87000 R08: 0000000000000000 R09: fffffbfff2244efa R10: ffffc9000374fa40 R11: 0000000000000000 R12: 00000000fffffffe R13: ffff88802ff870e8 R14: 0000000000000008 R15: 0000000000000000 FS: 000055556cf07500(0000) GS:ffff8880d5ddc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fc48295da08 CR3: 000000003cd5d000 CR4: 0000000000352ef0 ---------------- Code disassembly (best guess): 0: 90 nop 1: 90 nop 2: 90 nop 3: 90 nop 4: 90 nop 5: 90 nop 6: 90 nop 7: 90 nop 8: 90 nop 9: 90 nop a: f3 0f 1e fa endbr64 e: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 15: fc ff df 18: 41 54 push %r12 1a: 55 push %rbp 1b: 53 push %rbx 1c: 48 89 fb mov %rdi,%rbx 1f: 48 83 c7 08 add $0x8,%rdi 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2e: 0f 85 5b 01 00 00 jne 0x18f 34: 48 89 da mov %rbx,%rdx 37: 48 8b 6b 08 mov 0x8(%rbx),%rbp 3b: 48 rex.W 3c: b8 .byte 0xb8 3d: 00 00 add %al,(%rax) --- 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@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup