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

[syzbot <syzbot+bbb6dad313f4aaa8da6b@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in f_midi2_stop_eps

Oops: general protection fault, probably for non-canonical address 0xdffffc00000000ee: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000770-0x0000000000000777]
CPU: 1 UID: 0 PID: 29 Comm: ktimers/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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 67 82 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 09
RSP: 0018:ffffc90000a3f6d8 EFLAGS: 00010206
RAX: 00000000000000ee RBX: ffff888032d2c120 RCX: ffff88801d2ebe00
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: ffff888032d2c100 R08: ffffffff8faf9f37 R09: 1ffffffff1f5f3e6
R10: dffffc0000000000 R11: fffffbfff1f5f3e7 R12: ffff888032d2c770
R13: dffffc0000000000 R14: ffff888032d2c128 R15: 0000000000000770
FS:  0000000000000000(0000) GS:ffff888125d3e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f590008b0f5 CR3: 0000000042aa6000 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+0x2f77/0x4d50 drivers/usb/gadget/udc/dummy_hcd.c:1951
 __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 67 82 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 09
RSP: 0018:ffffc90000a3f6d8 EFLAGS: 00010206
RAX: 00000000000000ee RBX: ffff888032d2c120 RCX: ffff88801d2ebe00
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: ffff888032d2c100 R08: ffffffff8faf9f37 R09: 1ffffffff1f5f3e6
R10: dffffc0000000000 R11: fffffbfff1f5f3e7 R12: ffff888032d2c770
R13: dffffc0000000000 R14: ffff888032d2c128 R15: 0000000000000770
FS:  0000000000000000(0000) GS:ffff888125d3e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f590008b0f5 CR3: 0000000042aa6000 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 67 82 e7 fa       	call   0xfae7827c
  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:	09                   	.byte 0x9


Tested on:

commit:         3708dd94 Merge tag 'pm-7.2-rc6' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=158925b9580000
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

Note: no patches were applied.