possible deadlock in genl_rcv

Status: upstream: reported on 2026/09/24 17:02
Reported-by: syzbot+0e2d637ad91ca5881104@syzkaller.appspotmail.com
First crash: 3d19h, last: 2d06h
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in genl_rcv (4) prio:low autofs 4 57 3d04h 126d 0/29 upstream: reported on 2026/05/24 13:47
linux-5.15 possible deadlock in genl_rcv 4 3 31d 122d 0/3 upstream: reported on 2026/05/29 04:19
upstream possible deadlock in genl_rcv net 4 1 3215d 3211d 0/29 closed as invalid on 2018/02/13 19:42
linux-6.6 possible deadlock in genl_rcv 4 3 3d15h 30d 0/2 upstream: reported on 2026/08/29 00:22
linux-4.19 possible deadlock in genl_rcv (2) 4 1 1780d 1780d 0/1 auto-closed as invalid on 2022/03/12 20:05
upstream possible deadlock in genl_rcv (3) net 4 1 1737d 1733d 0/29 auto-closed as invalid on 2022/04/25 11:14
linux-4.19 possible deadlock in genl_rcv 4 1 2399d 2399d 0/1 auto-closed as invalid on 2020/07/02 11:07
upstream possible deadlock in genl_rcv (2) net 4 2 2757d 2817d 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.0.6615/26015 is trying to acquire lock:
ffffffff8ddb5b90 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:860

but task is already holding lock:
ffff88807de9ac68 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_from_pipe fs/splice.c:592 [inline]
ffff88807de9ac68 (&pipe->mutex/1){+.+.}-{3:3}, at: generic_splice_sendpage+0xff/0x180 fs/splice.c:742

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+0x12d/0xae0 kernel/locking/mutex.c:747
       iter_file_splice_write+0x1b6/0xcf0 fs/splice.c:631
       do_splice_from fs/splice.c:763 [inline]
       do_splice+0xe46/0x1620 fs/splice.c:1102
       __do_splice fs/splice.c:1167 [inline]
       __do_sys_splice fs/splice.c:1374 [inline]
       __se_sys_splice+0x34d/0x440 fs/splice.c:1356
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 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:1897 [inline]
       sb_start_write+0x4d/0x1c0 include/linux/fs.h:1972
       mnt_want_write+0x3d/0x90 fs/namespace.c:402
       open_last_lookups fs/namei.c:3590 [inline]
       path_openat+0x75c/0x2f10 fs/namei.c:3831
       do_filp_open+0x1ee/0x420 fs/namei.c:3861
       file_open_name fs/open.c:1265 [inline]
       filp_open+0x17c/0x1e0 fs/open.c:1285
       fsg_lun_open+0x63/0xf00 drivers/usb/gadget/function/storage_common.c:193
       fsg_store_file+0x1a5/0x530 drivers/usb/gadget/function/storage_common.c:454
       flush_write_buffer fs/configfs/file.c:207 [inline]
       configfs_write_iter+0x30b/0x400 fs/configfs/file.c:229
       call_write_iter include/linux/fs.h:2271 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x482/0x9a0 fs/read_write.c:584
       ksys_write+0x14d/0x260 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #4 (&common->filesem){++++}-{3:3}:
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       fsg_show_file+0x29/0x130 drivers/usb/gadget/function/storage_common.c:338
       fill_read_buffer fs/configfs/file.c:68 [inline]
       configfs_read_iter+0x296/0x560 fs/configfs/file.c:88
       __kernel_read+0x2dd/0x6e0 fs/read_write.c:428
       integrity_kernel_read+0x86/0xd0 security/integrity/iint.c:228
       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+0xb12/0x1950 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x503/0xb50 security/integrity/ima/ima_api.c:293
       process_measurement+0x119b/0x1c40 security/integrity/ima/ima_main.c:351
       ima_file_check+0xc8/0x110 security/integrity/ima/ima_main.c:534
       do_open fs/namei.c:3679 [inline]
       path_openat+0x272b/0x2f10 fs/namei.c:3834
       do_filp_open+0x1ee/0x420 fs/namei.c:3861
       do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
       do_sys_open fs/open.c:1336 [inline]
       __do_sys_openat fs/open.c:1352 [inline]
       __se_sys_openat fs/open.c:1347 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1347
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #3 (&p->frag_sem){++++}-{3:3}:
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       fill_read_buffer fs/configfs/file.c:66 [inline]
       configfs_read_iter+0x19e/0x560 fs/configfs/file.c:88
       __kernel_read+0x2dd/0x6e0 fs/read_write.c:428
       integrity_kernel_read+0x86/0xd0 security/integrity/iint.c:228
       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+0xb12/0x1950 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x503/0xb50 security/integrity/ima/ima_api.c:293
       process_measurement+0x119b/0x1c40 security/integrity/ima/ima_main.c:351
       ima_file_check+0xc8/0x110 security/integrity/ima/ima_main.c:534
       do_open fs/namei.c:3679 [inline]
       path_openat+0x272b/0x2f10 fs/namei.c:3834
       do_filp_open+0x1ee/0x420 fs/namei.c:3861
       do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
       do_sys_open fs/open.c:1336 [inline]
       __do_sys_openat fs/open.c:1352 [inline]
       __se_sys_openat fs/open.c:1347 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1347
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&buffer->mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12d/0xae0 kernel/locking/mutex.c:747
       configfs_read_iter+0x6e/0x560 fs/configfs/file.c:86
       __kernel_read+0x2dd/0x6e0 fs/read_write.c:428
       integrity_kernel_read+0x86/0xd0 security/integrity/iint.c:228
       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+0xb12/0x1950 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x503/0xb50 security/integrity/ima/ima_api.c:293
       process_measurement+0x119b/0x1c40 security/integrity/ima/ima_main.c:351
       ima_file_check+0xc8/0x110 security/integrity/ima/ima_main.c:534
       do_open fs/namei.c:3679 [inline]
       path_openat+0x272b/0x2f10 fs/namei.c:3834
       do_filp_open+0x1ee/0x420 fs/namei.c:3861
       do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
       do_sys_open fs/open.c:1336 [inline]
       __do_sys_openat fs/open.c:1352 [inline]
       __se_sys_openat fs/open.c:1347 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1347
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 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+0x12d/0xae0 kernel/locking/mutex.c:747
       process_measurement+0x717/0x1c40 security/integrity/ima/ima_main.c:261
       ima_file_check+0xc8/0x110 security/integrity/ima/ima_main.c:534
       do_open fs/namei.c:3679 [inline]
       path_openat+0x272b/0x2f10 fs/namei.c:3834
       do_file_open_root+0x2ef/0x5a0 fs/namei.c:3886
       file_open_root+0x163/0x1c0 fs/open.c:1300
       kernel_read_file_from_path_initns+0x14d/0x220 fs/kernel_read_file.c:163
       fw_get_filesystem_firmware drivers/base/firmware_loader/main.c:539 [inline]
       _request_firmware+0x895/0x1280 drivers/base/firmware_loader/main.c:859
       request_firmware+0x32/0x50 drivers/base/firmware_loader/main.c:933
       reg_reload_regdb+0x96/0x490 net/wireless/reg.c:1116
       genl_family_rcv_msg_doit+0x22f/0x350 net/netlink/genetlink.c:756
       genl_family_rcv_msg net/netlink/genetlink.c:833 [inline]
       genl_rcv_msg+0x601/0x790 net/netlink/genetlink.c:850
       netlink_rcv_skb+0x1ef/0x440 net/netlink/af_netlink.c:2516
       genl_rcv+0x24/0x40 net/netlink/genetlink.c:861
       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
       netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
       netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
       sock_sendmsg_nosec net/socket.c:718 [inline]
       __sock_sendmsg net/socket.c:730 [inline]
       ____sys_sendmsg+0x5ed/0x9a0 net/socket.c:2519
       ___sys_sendmsg+0x2a2/0x360 net/socket.c:2573
       __sys_sendmsg net/socket.c:2602 [inline]
       __do_sys_sendmsg net/socket.c:2611 [inline]
       __se_sys_sendmsg+0x1c3/0x2b0 net/socket.c:2609
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 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:3095 [inline]
       check_prevs_add kernel/locking/lockdep.c:3214 [inline]
       validate_chain kernel/locking/lockdep.c:3830 [inline]
       __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       genl_rcv+0x15/0x40 net/netlink/genetlink.c:860
       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
       netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
       netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
       sock_sendmsg_nosec net/socket.c:718 [inline]
       __sock_sendmsg net/socket.c:730 [inline]
       sock_sendmsg net/socket.c:753 [inline]
       kernel_sendmsg+0x246/0x370 net/socket.c:777
       sock_no_sendpage+0x137/0x1c0 net/core/sock.c:3268
       kernel_sendpage+0x27d/0x570 net/socket.c:3606
       sock_sendpage+0x7a/0xb0 net/socket.c:1082
       pipe_to_sendpage+0x22f/0x320 fs/splice.c:360
       splice_from_pipe_feed fs/splice.c:414 [inline]
       __splice_from_pipe+0x333/0x8e0 fs/splice.c:558
       splice_from_pipe fs/splice.c:593 [inline]
       generic_splice_sendpage+0x111/0x180 fs/splice.c:742
       do_splice_from fs/splice.c:763 [inline]
       do_splice+0xe46/0x1620 fs/splice.c:1102
       __do_splice fs/splice.c:1167 [inline]
       __do_sys_splice fs/splice.c:1374 [inline]
       __se_sys_splice+0x34d/0x440 fs/splice.c:1356
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 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);
  lock(cb_lock);

 *** DEADLOCK ***

1 lock held by syz.0.6615/26015:
 #0: ffff88807de9ac68 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_from_pipe fs/splice.c:592 [inline]
 #0: ffff88807de9ac68 (&pipe->mutex/1){+.+.}-{3:3}, at: generic_splice_sendpage+0xff/0x180 fs/splice.c:742

stack backtrace:
CPU: 1 PID: 26015 Comm: syz.0.6615 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3095 [inline]
 check_prevs_add kernel/locking/lockdep.c:3214 [inline]
 validate_chain kernel/locking/lockdep.c:3830 [inline]
 __lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678
 down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
 genl_rcv+0x15/0x40 net/netlink/genetlink.c:860
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x7ad/0x920 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 sock_sendmsg net/socket.c:753 [inline]
 kernel_sendmsg+0x246/0x370 net/socket.c:777
 sock_no_sendpage+0x137/0x1c0 net/core/sock.c:3268
 kernel_sendpage+0x27d/0x570 net/socket.c:3606
 sock_sendpage+0x7a/0xb0 net/socket.c:1082
 pipe_to_sendpage+0x22f/0x320 fs/splice.c:360
 splice_from_pipe_feed fs/splice.c:414 [inline]
 __splice_from_pipe+0x333/0x8e0 fs/splice.c:558
 splice_from_pipe fs/splice.c:593 [inline]
 generic_splice_sendpage+0x111/0x180 fs/splice.c:742
 do_splice_from fs/splice.c:763 [inline]
 do_splice+0xe46/0x1620 fs/splice.c:1102
 __do_splice fs/splice.c:1167 [inline]
 __do_sys_splice fs/splice.c:1374 [inline]
 __se_sys_splice+0x34d/0x440 fs/splice.c:1356
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f59a879e159
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:00007f59a95ee028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f59a8a25fa0 RCX: 00007f59a879e159
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f59a883506b R08: 000000000000fffd R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f59a8a26038 R14: 00007f59a8a25fa0 R15: 00007fffdf742418
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/26 05:18 linux-6.1.y 1a8763b93150 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in genl_rcv
2026/09/26 05:18 linux-6.1.y 1a8763b93150 a3c7249d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in genl_rcv
2026/09/24 17:02 linux-6.1.y 1a8763b93150 3c3cdf19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in genl_rcv
2026/09/24 17:02 linux-6.1.y 1a8763b93150 3c3cdf19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in genl_rcv
* Struck through repros no longer work on HEAD.