[syzbot] [usb?] possible deadlock in uvcg_default_output_i_terminal_show

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0d8395707651 Merge tag 'soc-fixes-7.2-2' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10ec7cc6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782
dashboard link: https://syzkaller.appspot.com/bug?extid=a5ab3e09c246a659fe9c
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-0d839570.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0b7275b6c889/vmlinux-0d839570.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b752a676c1dd/bzImage-0d839570.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a5ab3e...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G L
------------------------------------------------------
syz.5.3720/17064 is trying to acquire lock:
ffffffff901d0fe8 (gadget_subsys.su_mutex){+.+.}-{4:4}, at: uvcg_default_output_i_terminal_show+0x49/0x180 drivers/usb/gadget/function/uvc_configfs.c:671

but task is already holding lock:
ffff888025961970 (&p->frag_sem){++++}-{4:4}, at: fill_read_buffer fs/configfs/file.c:66 [inline]
ffff888025961970 (&p->frag_sem){++++}-{4:4}, at: configfs_read_iter+0x346/0x6f0 fs/configfs/file.c:88

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&p->frag_sem){++++}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
down_write_killable+0x93/0x250 kernel/locking/rwsem.c:1643
configfs_rmdir+0x3fa/0x950 fs/configfs/dir.c:1534
vfs_rmdir fs/namei.c:5381 [inline]
vfs_rmdir+0x328/0x8a0 fs/namei.c:5354
filename_rmdir+0x31a/0x5c0 fs/namei.c:5438
__do_sys_rmdir fs/namei.c:5461 [inline]
__se_sys_rmdir fs/namei.c:5458 [inline]
__x64_sys_rmdir+0x46/0x70 fs/namei.c:5458
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

-> #2 (&sb->s_type->i_mutex_key#24){++++}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
inode_lock include/linux/fs.h:1024 [inline]
configfs_depend_item_unlocked+0xf3/0x6a0 fs/configfs/dir.c:1259
usbg_make_tpg+0x261/0x620 drivers/usb/gadget/function/f_tcm.c:1686
target_fabric_make_tpg+0xab/0x8c0 drivers/target/target_core_fabric_configfs.c:939
configfs_mkdir+0x51e/0xb70 fs/configfs/dir.c:1360
vfs_mkdir+0x361/0x850 fs/namei.c:5276
filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309
__do_sys_mkdirat fs/namei.c:5330 [inline]
__se_sys_mkdirat fs/namei.c:5327 [inline]
__x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5327
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

-> #1 (&opts->dep_lock){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
tcm_set_name+0x29/0xb0 drivers/usb/gadget/function/f_tcm.c:2669
function_make+0x21c/0x3f0 drivers/usb/gadget/configfs.c:636
configfs_mkdir+0x51e/0xb70 fs/configfs/dir.c:1360
vfs_mkdir+0x361/0x850 fs/namei.c:5276
filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309
__do_sys_mkdirat fs/namei.c:5330 [inline]
__se_sys_mkdirat fs/namei.c:5327 [inline]
__x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5327
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

-> #0
(
gadget_subsys.su_mutex){+.+.}-{4:4}:
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
uvcg_default_output_i_terminal_show+0x49/0x180 drivers/usb/gadget/function/uvc_configfs.c:671
fill_read_buffer fs/configfs/file.c:68 [inline]
configfs_read_iter+0x426/0x6f0 fs/configfs/file.c:88
__kernel_read+0x397/0xad0 fs/read_write.c:532
integrity_kernel_read+0x7e/0xb0 security/integrity/iint.c:28
ima_calc_file_hash_tfm+0x25e/0x350 security/integrity/ima/ima_crypto.c:222
ima_calc_file_hash+0x1e3/0x380 security/integrity/ima/ima_crypto.c:280
ima_collect_measurement+0x94f/0xb30 security/integrity/ima/ima_api.c:300
process_measurement+0xdfe/0x2350 security/integrity/ima/ima_main.c:425
ima_file_check+0xc3/0x110 security/integrity/ima/ima_main.c:685
security_file_post_open+0xc4/0x210 security/security.c:2755
do_open fs/namei.c:4702 [inline]
path_openat+0x985/0x4280 fs/namei.c:4863
do_file_open+0x20e/0x430 fs/namei.c:4892
do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1385
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

other info that might help us debug this:

Chain exists of:
gadget_subsys.su_mutex --> &sb->s_type->i_mutex_key#24 --> &p->frag_sem

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
rlock(&p->frag_sem);
lock(&sb->s_type->i_mutex_key#24);
lock(&p->frag_sem);
lock(gadget_subsys.su_mutex);

*** DEADLOCK ***

3 locks held by syz.5.3720/17064:
#0: ffff88802bcb8ab0 (&ima_iint_mutex_key[depth]){+.+.}-{4:4}, at: process_measurement+0x5ab/0x2350 security/integrity/ima/ima_main.c:319
#1: ffff888053449c80 (&buffer->mutex){+.+.}-{4:4}, at: configfs_read_iter+0x79/0x6f0 fs/configfs/file.c:86
#2: ffff888025961970 (&p->frag_sem){++++}-{4:4}, at: fill_read_buffer fs/configfs/file.c:66 [inline]
#2: ffff888025961970 (&p->frag_sem){++++}-{4:4}, at: configfs_read_iter+0x346/0x6f0 fs/configfs/file.c:88

stack backtrace:
CPU: 1 UID: 0 PID: 17064 Comm: syz.5.3720 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043
check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3165
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x136c/0x1a40 kernel/locking/lockdep.c:5237
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
uvcg_default_output_i_terminal_show+0x49/0x180 drivers/usb/gadget/function/uvc_configfs.c:671
fill_read_buffer fs/configfs/file.c:68 [inline]
configfs_read_iter+0x426/0x6f0 fs/configfs/file.c:88
__kernel_read+0x397/0xad0 fs/read_write.c:532
integrity_kernel_read+0x7e/0xb0 security/integrity/iint.c:28
ima_calc_file_hash_tfm+0x25e/0x350 security/integrity/ima/ima_crypto.c:222
ima_calc_file_hash+0x1e3/0x380 security/integrity/ima/ima_crypto.c:280
ima_collect_measurement+0x94f/0xb30 security/integrity/ima/ima_api.c:300
process_measurement+0xdfe/0x2350 security/integrity/ima/ima_main.c:425
ima_file_check+0xc3/0x110 security/integrity/ima/ima_main.c:685
security_file_post_open+0xc4/0x210 security/security.c:2755
do_open fs/namei.c:4702 [inline]
path_openat+0x985/0x4280 fs/namei.c:4863
do_file_open+0x20e/0x430 fs/namei.c:4892
do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1385
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: 0033:0x7fb58099e0d9
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:00007fb581891028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb580c25fa0 RCX: 00007fb58099e0d9
RDX: 0000000000000000 RSI: 0000200000000800 RDI: ffffffffffffff9c
RBP: 00007fb580a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb580c26038 R14: 00007fb580c25fa0 R15: 00007ffec8a97b18
</TASK>


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