From: syzbot <syzbot+3451bfda4264c512ef27@syzkaller.appspotmail.com>
To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [usb?] general protection fault in f_midi2_free_ep
Date: Wed, 29 Jul 2026 20:53:28 -0700 [thread overview]
Message-ID: <6a6acab8.57649fcc.360844.000f.GAE@google.com> (raw)
In-Reply-To: <6a68b458.4c659fcc.19cd90.0023.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: fc46aed51f62 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=142cd9b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=cb17729fb04b1e3a
dashboard link: https://syzkaller.appspot.com/bug?extid=3451bfda4264c512ef27
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=12ab248e580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=118ab8c6580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/955cec68f017/disk-fc46aed5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a9cb903c7039/vmlinux-fc46aed5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/54a5b24a2b25/bzImage-fc46aed5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3451bfda4264c512ef27@syzkaller.appspotmail.com
Oops: gen[ 99.553665][ T5620] 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: 5620 Comm: syz-executor121 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_free_ep+0x52/0x2f0 drivers/usb/gadget/function/f_midi2.c:1208
Code: 4c 89 f0 48 c1 e8 03 80 3c 28 00 74 08 4c 89 f7 e8 23 9d e7 fa 41 bc 70 07 00 00 4d 03 26 4c 89 e0 48 c1 e8 03 48 89 44 24 30 <0f> b6 04 28 84 c0 0f 85 5d 02 00 00 41 8b 1c 24 31 ff 89 de e8 d5
RSP: 0018:ffffc900040df978 EFLAGS: 00010206
RAX: 00000000000000ee RBX: ffff8880446f4000 RCX: ffff888038dcdd00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffffffff8faf9837 R09: 1ffffffff1f5f306
R10: dffffc0000000000 R11: fffffbfff1f5f307 R12: 0000000000000770
R13: dffffc0000000000 R14: ffff8880446f4128 R15: dffffc0000000000
FS: 000055558593b400(0000) GS:ffff888125c41000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005653470e07a0 CR3: 0000000042ae2000 CR4: 00000000003526f0
Call Trace:
<TASK>
f_midi2_unbind+0x9b/0x340 drivers/usb/gadget/function/f_midi2.c:2066
purge_configs_funcs+0x248/0x3d0 drivers/usb/gadget/configfs.c:1600
configfs_composite_unbind+0xa0/0x1b0 drivers/usb/gadget/configfs.c:1846
gadget_unbind_driver+0x1cb/0x410 drivers/usb/gadget/udc/core.c:1724
device_remove drivers/base/dd.c:616 [inline]
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x48b/0x880 drivers/base/dd.c:1372
driver_detach+0x1f3/0x2d0 drivers/base/dd.c:1435
bus_remove_driver+0x229/0x320 drivers/base/bus.c:832
usb_gadget_unregister_driver+0x4e/0x70 drivers/usb/gadget/udc/core.c:1784
unregister_gadget drivers/usb/gadget/configfs.c:263 [inline]
gadget_dev_desc_UDC_store+0x17a/0x2f0 drivers/usb/gadget/configfs.c:290
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x33a/0x430 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61e/0xbb0 fs/read_write.c:687
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd367807789
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd35b431c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 6769666e6f632f2e RCX: 00007fd367807789
RDX: 0000000000000001 RSI: 00002000000004c0 RDI: 0000000000000004
RBP: 6e6f635f796d2f2e R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 00007ffd35b43338
R13: 431bde82d7b634db R14: 00007fd36789ac40 R15: 0000000000000002
</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_free_ep+0x52/0x2f0 drivers/usb/gadget/function/f_midi2.c:1208
Code: 4c 89 f0 48 c1 e8 03 80 3c 28 00 74 08 4c 89 f7 e8 23 9d e7 fa 41 bc 70 07 00 00 4d 03 26 4c 89 e0 48 c1 e8 03 48 89 44 24 30 <0f> b6 04 28 84 c0 0f 85 5d 02 00 00 41 8b 1c 24 31 ff 89 de e8 d5
RSP: 0018:ffffc900040df978 EFLAGS: 00010206
RAX: 00000000000000ee RBX: ffff8880446f4000 RCX: ffff888038dcdd00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffffffff8faf9837 R09: 1ffffffff1f5f306
R10: dffffc0000000000 R11: fffffbfff1f5f307 R12: 0000000000000770
R13: dffffc0000000000 R14: ffff8880446f4128 R15: dffffc0000000000
FS: 000055558593b400(0000) GS:ffff888125c41000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005653470e07a0 CR3: 0000000042ae2000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 4c 89 f0 mov %r14,%rax
3: 48 c1 e8 03 shr $0x3,%rax
7: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1)
b: 74 08 je 0x15
d: 4c 89 f7 mov %r14,%rdi
10: e8 23 9d e7 fa call 0xfae79d38
15: 41 bc 70 07 00 00 mov $0x770,%r12d
1b: 4d 03 26 add (%r14),%r12
1e: 4c 89 e0 mov %r12,%rax
21: 48 c1 e8 03 shr $0x3,%rax
25: 48 89 44 24 30 mov %rax,0x30(%rsp)
* 2a: 0f b6 04 28 movzbl (%rax,%rbp,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 0f 85 5d 02 00 00 jne 0x293
36: 41 8b 1c 24 mov (%r12),%ebx
3a: 31 ff xor %edi,%edi
3c: 89 de mov %ebx,%esi
3e: e8 .byte 0xe8
3f: d5 .byte 0xd5
---
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.
next prev parent reply other threads:[~2026-07-30 3:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-28 13:53 [syzbot] [usb?] general protection fault in f_midi2_free_ep syzbot
2026-07-30 3:53 ` syzbot [this message]
2026-07-30 11:27 ` Aleksandr Nogikh
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