possible deadlock in genl_rcv

Status: upstream: reported on 2026/08/29 00:22
Reported-by: syzbot+949ac3e5fb16bfd2be2c@syzkaller.appspotmail.com
First crash: 1d18h, last: 1d18h
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in genl_rcv (4) prio:low net 4 49 5h55m 98d 0/29 upstream: reported on 2026/05/24 13:47
linux-5.15 possible deadlock in genl_rcv 4 3 3d01h 93d 0/3 upstream: reported on 2026/05/29 04:19
upstream possible deadlock in genl_rcv net 4 1 3187d 3182d 0/29 closed as invalid on 2018/02/13 19:42
linux-4.19 possible deadlock in genl_rcv (2) 4 1 1751d 1751d 0/1 auto-closed as invalid on 2022/03/12 20:05
upstream possible deadlock in genl_rcv (3) net 4 1 1708d 1704d 0/29 auto-closed as invalid on 2022/04/25 11:14
linux-4.19 possible deadlock in genl_rcv 4 1 2370d 2370d 0/1 auto-closed as invalid on 2020/07/02 11:07
upstream possible deadlock in genl_rcv (2) net 4 2 2728d 2788d 0/29 auto-closed as invalid on 2019/09/08 03:35

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.3334/17789 is trying to acquire lock:
ffffffff8e43c430 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1074

but task is already holding lock:
ffff88805e2b0068 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_to_socket+0x163/0x1270 fs/splice.c:801

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #6 (&pipe->mutex/1){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
       iter_file_splice_write+0x1ba/0xcf0 fs/splice.c:683
       do_splice_from fs/splice.c:933 [inline]
       do_splice+0xe45/0x1b20 fs/splice.c:1292
       __do_splice fs/splice.c:1370 [inline]
       __do_sys_splice fs/splice.c:1586 [inline]
       __se_sys_splice+0x398/0x4a0 fs/splice.c:1568
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #5 (sb_writers#5){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1633 [inline]
       sb_start_write+0x4d/0x1c0 include/linux/fs.h:1708
       mnt_want_write+0x41/0x90 fs/namespace.c:412
       open_last_lookups fs/namei.c:3596 [inline]
       path_openat+0x768/0x3270 fs/namei.c:3841
       do_filp_open+0x1f2/0x430 fs/namei.c:3871
       file_open_name fs/open.c:1367 [inline]
       filp_open+0x180/0x1e0 fs/open.c:1387
       fsg_lun_open+0x67/0xec0 drivers/usb/gadget/function/storage_common.c:194
       fsg_store_file+0x1a9/0x530 drivers/usb/gadget/function/storage_common.c:455
       flush_write_buffer fs/configfs/file.c:207 [inline]
       configfs_write_iter+0x312/0x400 fs/configfs/file.c:229
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x474/0x9a0 fs/read_write.c:584
       ksys_write+0x151/0x260 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #4 (&common->filesem){++++}-{3:3}:
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       fsg_show_file+0x2d/0x130 drivers/usb/gadget/function/storage_common.c:339
       fill_read_buffer fs/configfs/file.c:68 [inline]
       configfs_read_iter+0x29d/0x570 fs/configfs/file.c:88
       __kernel_read+0x2e5/0x730 fs/read_write.c:428
       integrity_kernel_read+0x8a/0xd0 security/integrity/iint.c:221
       ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
       ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
       ima_calc_file_hash+0xb1f/0x1960 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x4d4/0xa30 security/integrity/ima/ima_api.c:290
       process_measurement+0x123a/0x1d50 security/integrity/ima/ima_main.c:370
       ima_file_check+0xcc/0x110 security/integrity/ima/ima_main.c:568
       do_open fs/namei.c:3685 [inline]
       path_openat+0x2910/0x3270 fs/namei.c:3844
       do_filp_open+0x1f2/0x430 fs/namei.c:3871
       do_sys_openat2+0x134/0x1d0 fs/open.c:1422
       do_sys_open fs/open.c:1437 [inline]
       __do_sys_openat fs/open.c:1453 [inline]
       __se_sys_openat fs/open.c:1448 [inline]
       __x64_sys_openat+0x139/0x160 fs/open.c:1448
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #3 (&p->frag_sem){.+.+}-{3:3}:
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       fill_read_buffer fs/configfs/file.c:66 [inline]
       configfs_read_iter+0x1a5/0x570 fs/configfs/file.c:88
       __kernel_read+0x2e5/0x730 fs/read_write.c:428
       integrity_kernel_read+0x8a/0xd0 security/integrity/iint.c:221
       ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
       ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
       ima_calc_file_hash+0xb1f/0x1960 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x4d4/0xa30 security/integrity/ima/ima_api.c:290
       process_measurement+0x123a/0x1d50 security/integrity/ima/ima_main.c:370
       ima_file_check+0xcc/0x110 security/integrity/ima/ima_main.c:568
       do_open fs/namei.c:3685 [inline]
       path_openat+0x2910/0x3270 fs/namei.c:3844
       do_filp_open+0x1f2/0x430 fs/namei.c:3871
       do_sys_openat2+0x134/0x1d0 fs/open.c:1422
       do_sys_open fs/open.c:1437 [inline]
       __do_sys_openat fs/open.c:1453 [inline]
       __se_sys_openat fs/open.c:1448 [inline]
       __x64_sys_openat+0x139/0x160 fs/open.c:1448
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&buffer->mutex#2){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
       configfs_read_iter+0x72/0x570 fs/configfs/file.c:86
       __kernel_read+0x2e5/0x730 fs/read_write.c:428
       integrity_kernel_read+0x8a/0xd0 security/integrity/iint.c:221
       ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
       ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
       ima_calc_file_hash+0xb1f/0x1960 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x4d4/0xa30 security/integrity/ima/ima_api.c:290
       process_measurement+0x123a/0x1d50 security/integrity/ima/ima_main.c:370
       ima_file_check+0xcc/0x110 security/integrity/ima/ima_main.c:568
       do_open fs/namei.c:3685 [inline]
       path_openat+0x2910/0x3270 fs/namei.c:3844
       do_filp_open+0x1f2/0x430 fs/namei.c:3871
       do_sys_openat2+0x134/0x1d0 fs/open.c:1422
       do_sys_open fs/open.c:1437 [inline]
       __do_sys_openat fs/open.c:1453 [inline]
       __se_sys_openat fs/open.c:1448 [inline]
       __x64_sys_openat+0x139/0x160 fs/open.c:1448
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&iint_mutex_key[depth]){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x135/0xc80 kernel/locking/mutex.c:747
       process_measurement+0x739/0x1d50 security/integrity/ima/ima_main.c:275
       ima_file_check+0xcc/0x110 security/integrity/ima/ima_main.c:568
       do_open fs/namei.c:3685 [inline]
       path_openat+0x2910/0x3270 fs/namei.c:3844
       do_file_open_root+0x2f3/0x5a0 fs/namei.c:3896
       file_open_root+0x167/0x1c0 fs/open.c:1402
       kernel_read_file_from_path_initns+0x151/0x230 fs/kernel_read_file.c:163
       fw_get_filesystem_firmware drivers/base/firmware_loader/main.c:548 [inline]
       _request_firmware+0xb43/0x1520 drivers/base/firmware_loader/main.c:911
       request_firmware+0x36/0x50 drivers/base/firmware_loader/main.c:987
       reg_reload_regdb+0x9a/0x490 net/wireless/reg.c:1078
       genl_family_rcv_msg_doit+0x21a/0x310 net/netlink/genetlink.c:971
       genl_family_rcv_msg net/netlink/genetlink.c:1051 [inline]
       genl_rcv_msg+0x611/0x7a0 net/netlink/genetlink.c:1066
       netlink_rcv_skb+0x235/0x4c0 net/netlink/af_netlink.c:2550
       genl_rcv+0x28/0x40 net/netlink/genetlink.c:1075
       netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
       netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
       netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
       sock_sendmsg_nosec net/socket.c:730 [inline]
       __sock_sendmsg net/socket.c:745 [inline]
       ____sys_sendmsg+0x61b/0x980 net/socket.c:2595
       ___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
       __sys_sendmsg net/socket.c:2678 [inline]
       __do_sys_sendmsg net/socket.c:2687 [inline]
       __se_sys_sendmsg+0x1d0/0x2c0 net/socket.c:2685
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (cb_lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       genl_rcv+0x19/0x40 net/netlink/genetlink.c:1074
       netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
       netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
       netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
       sock_sendmsg_nosec net/socket.c:730 [inline]
       __sock_sendmsg net/socket.c:745 [inline]
       sock_sendmsg+0x23b/0x3a0 net/socket.c:768
       splice_to_socket+0xb92/0x1270 fs/splice.c:881
       do_splice_from fs/splice.c:933 [inline]
       do_splice+0xe45/0x1b20 fs/splice.c:1292
       __do_splice fs/splice.c:1370 [inline]
       __do_sys_splice fs/splice.c:1586 [inline]
       __se_sys_splice+0x398/0x4a0 fs/splice.c:1568
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  cb_lock --> sb_writers#5 --> &pipe->mutex/1

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&pipe->mutex/1);
                               lock(sb_writers#5);
                               lock(&pipe->mutex/1);
  rlock(cb_lock);

 *** DEADLOCK ***

1 lock held by syz.6.3334/17789:
 #0: ffff88805e2b0068 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_to_socket+0x163/0x1270 fs/splice.c:801

stack backtrace:
CPU: 0 PID: 17789 Comm: syz.6.3334 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
 genl_rcv+0x19/0x40 net/netlink/genetlink.c:1074
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x7b1/0x930 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8d0/0xbf0 net/netlink/af_netlink.c:1899
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 sock_sendmsg+0x23b/0x3a0 net/socket.c:768
 splice_to_socket+0xb92/0x1270 fs/splice.c:881
 do_splice_from fs/splice.c:933 [inline]
 do_splice+0xe45/0x1b20 fs/splice.c:1292
 __do_splice fs/splice.c:1370 [inline]
 __do_sys_splice fs/splice.c:1586 [inline]
 __se_sys_splice+0x398/0x4a0 fs/splice.c:1568
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb24a19e159
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:00007fb24b081028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007fb24a425fa0 RCX: 00007fb24a19e159
RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fb24a235024 R08: 0000000000000800 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb24a426038 R14: 00007fb24a425fa0 R15: 00007ffe5a0faed8
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/29 00:21 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in genl_rcv
2026/08/29 00:21 linux-6.6.y a4a971135a2f 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in genl_rcv
* Struck through repros no longer work on HEAD.