Re: [syzbot] [fs?] VFS: Close: file count is zero (use-after-free) (2)

[syzbot <syzbot+592c653b056459925299@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    db2ddb871435 Linux 7.2-rc7
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12ce2079580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c44651ea7dd2f307
dashboard link: https://syzkaller.appspot.com/bug?extid=592c653b056459925299
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=15406079580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11745132580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-db2ddb87.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/698def9fcf7a/vmlinux-db2ddb87.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fd8b6091a563/bzImage-db2ddb87.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+592c653b056459925299@syzkaller.appspotmail.com

 slab filp start ffff888033422a80 pointer offset 0 size 352
VFS: Close: file count is 0 (f_op=snd_ctl_f_ops)
------------[ cut here ]------------
kernel BUG at fs/open.c:1464!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5911 Comm: syz.0.18 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:filp_flush.cold+0x30/0x39 fs/open.c:1464
Code: 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 80 3c 02 00 75 13 48 8b 73 48 48 c7 c7 20 a7 e5 8b e8 f9 4f fd ff 90 <0f> 0b e8 91 07 56 01 eb e6 e8 ca 78 e5 00 65 48 8b 2d 5a 45 3e 13
RSP: 0018:ffffc9000681f828 EFLAGS: 00010286
RAX: 0000000000000030 RBX: ffff888033422a80 RCX: 0000000000000000
RDX: 0000000000000030 RSI: ffffffff81e8bfd9 RDI: fffff52000d03ef6
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: e000000000000000
R13: bfffffffffffffff R14: ffff888027786528 R15: 0000000000000000
FS:  000055556f1f4500(0000) GS:ffff8880d5dec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb5d8c70000 CR3: 000000003c1d3000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 filp_close+0x1c/0x30 fs/open.c:1484
 gaudio_close_snd_dev drivers/usb/gadget/function/u_uac1_legacy.c:263 [inline]
 gaudio_cleanup+0x59/0x100 drivers/usb/gadget/function/u_uac1_legacy.c:305
 f_audio_bind+0x56c/0x660 drivers/usb/gadget/function/f_uac1_legacy.c:792
 usb_add_function+0x219/0x890 drivers/usb/gadget/composite.c:333
 configfs_composite_bind+0xd83/0x1960 drivers/usb/gadget/configfs.c:1802
 gadget_bind_driver+0x28c/0xbf0 drivers/usb/gadget/udc/core.c:1662
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
 bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
 driver_register+0x1e2/0x360 drivers/base/driver.c:174
 usb_gadget_register_driver_owner+0x132/0x210 drivers/usb/gadget/udc/core.c:1752
 gadget_dev_desc_UDC_store+0x1b0/0x2e0 drivers/usb/gadget/configfs.c:300
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
 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: 0033:0x7fb5d8d9e0d9
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:00007ffdccfb2e58 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fb5d9025fa0 RCX: 00007fb5d8d9e0d9
RDX: 000000000000000c RSI: 0000200000000400 RDI: 0000000000000003
RBP: 00007fb5d8e35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb5d9025fac R14: 00007fb5d9025fa0 R15: 00007fb5d9025fa0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:filp_flush.cold+0x30/0x39 fs/open.c:1464
Code: 8d 7b 48 b8 ff ff 37 00 48 89 fa 48 c1 e0 2a 48 c1 ea 03 80 3c 02 00 75 13 48 8b 73 48 48 c7 c7 20 a7 e5 8b e8 f9 4f fd ff 90 <0f> 0b e8 91 07 56 01 eb e6 e8 ca 78 e5 00 65 48 8b 2d 5a 45 3e 13
RSP: 0018:ffffc9000681f828 EFLAGS: 00010286
RAX: 0000000000000030 RBX: ffff888033422a80 RCX: 0000000000000000
RDX: 0000000000000030 RSI: ffffffff81e8bfd9 RDI: fffff52000d03ef6
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: e000000000000000
R13: bfffffffffffffff R14: ffff888027786528 R15: 0000000000000000
FS:  000055556f1f4500(0000) GS:ffff8880d5eec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdccfb3118 CR3: 000000003c1d3000 CR4: 0000000000352ef0


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