* Re: [syzbot] [integrity?] [lsm?] possible deadlock in __configfs_open_file (2)
[not found] <6a6aad2e.57649fcc.360844.000d.GAE@google.com>
@ 2026-10-13 22:22 ` syzbot
0 siblings, 0 replies; only message in thread
From: syzbot @ 2026-10-13 22:22 UTC (permalink / raw)
To: a.hindborg, leitao, linux-fsdevel, linux-integrity, linux-kernel,
linux-security-module, syzkaller-bugs
syzbot has found a reproducer for the following issue on:
HEAD commit: 24a19b953e2a Linux 7.3-rc7
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=165f3c35580000
kernel config: https://syzkaller.appspot.com/x/.config?x=129d675874dbf896
dashboard link: https://syzkaller.appspot.com/bug?extid=c87014f645f2fd24312e
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10cf93d1580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c87014f645f2fd24312e@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor387/5997 is trying to acquire lock:
ffff888035be1570 (&p->frag_sem){.+.+}-{4:4}, at: __configfs_open_file+0xe8/0x9c0 fs/configfs/file.c:304
but task is already holding lock:
ffffffff91d84848 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #3 (cb_lock){++++}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
down_read+0x99/0x4c0 kernel/locking/rwsem.c:1574
genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1364
netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:800 [inline]
__sock_sendmsg net/socket.c:815 [inline]
sock_sendmsg+0x394/0x410 net/socket.c:838
splice_to_socket+0xb3c/0x11a0 fs/splice.c:884
do_splice_from fs/splice.c:936 [inline]
do_splice+0x109c/0x1fa0 fs/splice.c:1349
__do_splice+0x33b/0x370 fs/splice.c:1431
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice fs/splice.c:1616 [inline]
__x64_sys_splice+0x187/0x250 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #2 (&pipe->mutex){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
__mutex_lock_common kernel/locking/mutex.c:646 [inline]
__mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
fifo_open+0x139/0xb40 fs/pipe.c:1235
do_dentry_open+0x6ab/0x14d0 fs/open.c:996
vfs_open+0x82/0x3f0 fs/open.c:1101
do_open fs/namei.c:4866 [inline]
path_openat+0x19fa/0x2440 fs/namei.c:5029
do_file_open+0x20e/0x430 fs/namei.c:5058
file_open_name+0x1c3/0x3e0 fs/open.c:1375
filp_open+0x2e/0x50 fs/open.c:1392
fsg_lun_open+0x6b/0x7b0 drivers/usb/gadget/function/storage_common.c:194
fsg_store_file+0x1e7/0x450 drivers/usb/gadget/function/storage_common.c:455
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+0x6af/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #1 (&common->filesem){+.+.}-{4:4}:
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
fsg_store_file+0x264/0x450 drivers/usb/gadget/function/storage_common.c:452
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+0x6af/0x1050 fs/read_write.c:687
ksys_write+0x12a/0x250 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (&p->frag_sem){.+.+}-{4:4}:
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
check_prevs_add kernel/locking/lockdep.c:3328 [inline]
validate_chain kernel/locking/lockdep.c:3952 [inline]
__lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
down_read+0x99/0x4c0 kernel/locking/rwsem.c:1574
__configfs_open_file+0xe8/0x9c0 fs/configfs/file.c:304
do_dentry_open+0x6ab/0x14d0 fs/open.c:996
vfs_open+0x82/0x3f0 fs/open.c:1101
do_open fs/namei.c:4866 [inline]
path_openat+0x19fa/0x2440 fs/namei.c:5029
do_file_open+0x20e/0x430 fs/namei.c:5058
file_open_name+0x1c3/0x3e0 fs/open.c:1375
filp_open+0x2e/0x50 fs/open.c:1392
kernel_read_file_from_path_initns+0xec/0x240 fs/kernel_read_file.c:159
fw_get_filesystem_firmware drivers/base/firmware_loader/main.c:549 [inline]
_request_firmware+0x733/0x13c0 drivers/base/firmware_loader/main.c:873
request_firmware+0x35/0x50 drivers/base/firmware_loader/main.c:948
reg_reload_regdb+0x85/0x460 net/wireless/reg.c:1067
genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2575
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1364
netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:800 [inline]
__sock_sendmsg net/socket.c:815 [inline]
sock_sendmsg+0x394/0x410 net/socket.c:838
splice_to_socket+0xb3c/0x11a0 fs/splice.c:884
do_splice_from fs/splice.c:936 [inline]
do_splice+0x109c/0x1fa0 fs/splice.c:1349
__do_splice+0x33b/0x370 fs/splice.c:1431
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice fs/splice.c:1616 [inline]
__x64_sys_splice+0x187/0x250 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Chain exists of:
&p->frag_sem --> &pipe->mutex --> cb_lock
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
rlock(cb_lock);
lock(&pipe->mutex);
lock(cb_lock);
rlock(&p->frag_sem);
*** DEADLOCK ***
locks held by syz-executor387/5997: 2, last CPU#0:
#0: ffff888035fc7860 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock fs/pipe.c:91 [inline]
#0: ffff888035fc7860 (&pipe->mutex){+.+.}-{4:4}, at: pipe_lock+0x69/0x80 fs/pipe.c:88
#1: ffffffff91d84848 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
stack backtrace:
CPU: 0 UID: 0 PID: 5997 Comm: syz-executor387 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
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+0x178/0x1be kernel/locking/lockdep.c:2087
check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219
check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209
check_prevs_add kernel/locking/lockdep.c:3328 [inline]
validate_chain kernel/locking/lockdep.c:3952 [inline]
__lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288
lock_acquire kernel/locking/lockdep.c:5942 [inline]
lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899
down_read+0x99/0x4c0 kernel/locking/rwsem.c:1574
__configfs_open_file+0xe8/0x9c0 fs/configfs/file.c:304
do_dentry_open+0x6ab/0x14d0 fs/open.c:996
vfs_open+0x82/0x3f0 fs/open.c:1101
do_open fs/namei.c:4866 [inline]
path_openat+0x19fa/0x2440 fs/namei.c:5029
do_file_open+0x20e/0x430 fs/namei.c:5058
file_open_name+0x1c3/0x3e0 fs/open.c:1375
filp_open+0x2e/0x50 fs/open.c:1392
kernel_read_file_from_path_initns+0xec/0x240 fs/kernel_read_file.c:159
fw_get_filesystem_firmware drivers/base/firmware_loader/main.c:549 [inline]
_request_firmware+0x733/0x13c0 drivers/base/firmware_loader/main.c:873
request_firmware+0x35/0x50 drivers/base/firmware_loader/main.c:948
reg_reload_regdb+0x85/0x460 net/wireless/reg.c:1067
genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2575
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1338 [inline]
netlink_unicast+0x585/0x850 net/netlink/af_netlink.c:1364
netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:800 [inline]
__sock_sendmsg net/socket.c:815 [inline]
sock_sendmsg+0x394/0x410 net/socket.c:838
splice_to_socket+0xb3c/0x11a0 fs/splice.c:884
do_splice_from fs/splice.c:936 [inline]
do_splice+0x109c/0x1fa0 fs/splice.c:1349
__do_splice+0x33b/0x370 fs/splice.c:1431
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice fs/splice.c:1616 [inline]
__x64_sys_splice+0x187/0x250 fs/splice.c:1616
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7180644b5e
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007f717cde6f18 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f717cde76c0 RCX: 00007f7180644b5e
RDX: 0000000000000010 RSI: 0000000000000000 RDI: 0000000000000011
RBP: 00007f717cde6fe0 R08: 0000000000000014 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000012
R13: 00007f717cde6f80 R14: 000000000000017e R15: 0000000000000010
</TASK>
faux_driver regulatory: loading /lib/firmware/regulatory.db failed with error -26
faux_driver regulatory: Direct firmware load for regulatory.db failed with error -26
faux_driver regulatory: Falling back to sysfs fallback for: regulatory.db
---
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.
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[not found] <6a6aad2e.57649fcc.360844.000d.GAE@google.com>
2026-10-13 22:22 ` [syzbot] [integrity?] [lsm?] possible deadlock in __configfs_open_file (2) syzbot
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