Dear Linux Developers for F_printer, We encountered "WARNING in usb_ep_queue" when testing the f_printer driver with Syzkaller and our generated specifications. I attached the report and C/syz reproducers for this crash. ``` ------------[ cut here ]------------ WARNING: CPU: 1 PID: 10395 at drivers/usb/gadget/udc/core.c:295 usb_ep_queue+0xa0/0x300 linux/drivers/usb/gadget/udc/core.c:295 Modules linked in: CPU: 1 PID: 10395 Comm: syz-executor364 Not tainted 6.6.0-gd2f51b3516da #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:usb_ep_queue+0xa0/0x300 linux/drivers/usb/gadget/udc/core.c:295 Code: 02 48 89 fa 83 e2 07 38 d0 7f 08 84 c0 0f 85 31 02 00 00 0f b6 5d 35 31 ff 89 de e8 da 51 08 fa 84 db 74 11 e8 01 56 08 fa 90 <0f> 0b 90 41 bd 94 ff ff ff eb 56 e8 f0 55 08 fa 48 8d 7d 10 48 b8 RSP: 0018:ffffc900075cfc00 EFLAGS: 00010093 RAX: 0000000000000000 RBX: 0000000000000081 RCX: ffffffff8786e5a6 RDX: ffff88801cd59e00 RSI: ffffffff8786e5af RDI: 0000000000000001 RBP: ffff8880173d80e0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000081 R11: 0000000000000000 R12: ffff888019236e10 R13: 0000000000000820 R14: 0000000000000000 R15: ffff888019236e58 FS: 000055555591d3c0(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020c55000 CR3: 0000000024d03000 CR4: 0000000000350ef0 Call Trace: <TASK> printer_write+0x650/0xf30 linux/drivers/usb/gadget/function/f_printer.c:669 vfs_write+0x2ae/0xd80 linux/fs/read_write.c:582 ksys_write+0x127/0x250 linux/fs/read_write.c:637 do_syscall_x64 linux/arch/x86/entry/common.c:51 [inline] do_syscall_64+0x40/0x110 linux/arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7f1c4a60e3bd Code: c3 e8 87 20 00 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd3d68a858 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007f1c4a60e3bd RDX: 000000000000004f RSI: 00000000200000c0 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007f1c4a663cd5 R09: 00007f1c4a663cd5 R10: 00237265746e6972 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffd3d68aab8 R14: 00007ffd3d68a880 R15: 00007ffd3d68a870 </TASK> ``` It seems that the `WARN_ON_ONCE(!ep->enabled && ep->address)` in usb_ep_queue (https://elixir.bootlin.com/linux/v6.7/source/drivers/usb/gadget/udc/core.c#L290), which is invoked by `printer_write` (https://elixir.bootlin.com/linux/v6.7/source/drivers/usb/gadget/function/f_printer.c#L669). If you have any questions or require more information, please feel free to contact us. Reported-by: Chenyuan Yang <chenyuan0y@xxxxxxxxx> Best, Chenyuan
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