possible deadlock in genl_rcv

Status: upstream: reported on 2026/05/29 04:19
Reported-by: syzbot+28ffde87cd851ffc1c52@syzkaller.appspotmail.com
First crash: 158d, last: 2d03h
▶ ▼ 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 65 12d 162d 0/29 upstream: reported on 2026/05/24 13:47
upstream possible deadlock in genl_rcv net 4 1 3251d 3246d 0/29 closed as invalid on 2018/02/13 19:42
linux-6.6 possible deadlock in genl_rcv 4 3 39d 66d 0/2 upstream: reported on 2026/08/29 00:22
linux-4.19 possible deadlock in genl_rcv (2) 4 1 1816d 1816d 0/1 auto-closed as invalid on 2022/03/12 20:05
linux-6.1 possible deadlock in genl_rcv 4 9 30d 39d 0/3 upstream: reported on 2026/09/24 17:02
upstream possible deadlock in genl_rcv (3) net 4 1 1772d 1768d 0/29 auto-closed as invalid on 2022/04/25 11:14
linux-4.19 possible deadlock in genl_rcv 4 1 2434d 2434d 0/1 auto-closed as invalid on 2020/07/02 11:07
upstream possible deadlock in genl_rcv (2) net 4 2 2793d 2852d 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.3.1135/8884 is trying to acquire lock:
ffffffff8e2c9a10 (cb_lock){++++}-{3:3}, at: genl_rcv+0x15/0x40 net/netlink/genetlink.c:802

but task is already holding lock:
ffff8880247b4068 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_from_pipe fs/splice.c:596 [inline]
ffff8880247b4068 (&pipe->mutex/1){+.+.}-{3:3}, at: generic_splice_sendpage+0xff/0x180 fs/splice.c:746

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+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       iter_file_splice_write+0x1b6/0xcf0 fs/splice.c:635
       do_splice_from fs/splice.c:767 [inline]
       do_splice+0xe51/0x1620 fs/splice.c:1108
       __do_splice fs/splice.c:1173 [inline]
       __do_sys_splice fs/splice.c:1379 [inline]
       __se_sys_splice+0x34d/0x440 fs/splice.c:1361
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #5 (sb_writers#3){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1817 [inline]
       sb_start_write+0x4f/0x1c0 include/linux/fs.h:1887
       mnt_want_write+0x3d/0x90 fs/namespace.c:386
       open_last_lookups fs/namei.c:3572 [inline]
       path_openat+0x795/0x2fb0 fs/namei.c:3790
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       file_open_name fs/open.c:1200 [inline]
       filp_open+0x17c/0x1e0 fs/open.c:1220
       fsg_lun_open+0x63/0xee0 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:2179 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x748/0xd70 fs/read_write.c:594
       ksys_write+0x153/0x260 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #4 (&common->filesem){++++}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       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+0x51d/0x980 fs/read_write.c:443
       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+0x946/0x1940 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x335/0x7e0 security/integrity/ima/ima_api.c:255
       process_measurement+0x1185/0x1c20 security/integrity/ima/ima_main.c:351
       ima_file_check+0xc7/0x110 security/integrity/ima/ima_main.c:533
       do_open fs/namei.c:3661 [inline]
       path_openat+0x27cf/0x2fb0 fs/namei.c:3793
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #3 (&p->frag_sem){.+.+}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       fill_read_buffer fs/configfs/file.c:66 [inline]
       configfs_read_iter+0x19e/0x560 fs/configfs/file.c:88
       __kernel_read+0x51d/0x980 fs/read_write.c:443
       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+0x946/0x1940 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x335/0x7e0 security/integrity/ima/ima_api.c:255
       process_measurement+0x1185/0x1c20 security/integrity/ima/ima_main.c:351
       ima_file_check+0xc7/0x110 security/integrity/ima/ima_main.c:533
       do_open fs/namei.c:3661 [inline]
       path_openat+0x27cf/0x2fb0 fs/namei.c:3793
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (&buffer->mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       configfs_read_iter+0x6e/0x560 fs/configfs/file.c:86
       __kernel_read+0x51d/0x980 fs/read_write.c:443
       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+0x946/0x1940 security/integrity/ima/ima_crypto.c:573
       ima_collect_measurement+0x335/0x7e0 security/integrity/ima/ima_api.c:255
       process_measurement+0x1185/0x1c20 security/integrity/ima/ima_main.c:351
       ima_file_check+0xc7/0x110 security/integrity/ima/ima_main.c:533
       do_open fs/namei.c:3661 [inline]
       path_openat+0x27cf/0x2fb0 fs/namei.c:3793
       do_filp_open+0x1df/0x400 fs/namei.c:3820
       do_sys_openat2+0x14b/0x500 fs/open.c:1255
       do_sys_open fs/open.c:1271 [inline]
       __do_sys_openat fs/open.c:1287 [inline]
       __se_sys_openat fs/open.c:1282 [inline]
       __x64_sys_openat+0x135/0x160 fs/open.c:1282
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&iint_mutex_key[depth]){+.+.}-{3:3}:
       __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       process_measurement+0x724/0x1c20 security/integrity/ima/ima_main.c:261
       ima_file_check+0xc7/0x110 security/integrity/ima/ima_main.c:533
       do_open fs/namei.c:3661 [inline]
       path_openat+0x27cf/0x2fb0 fs/namei.c:3793
       do_file_open_root+0x2e5/0x6b0 fs/namei.c:3845
       file_open_root+0x163/0x1c0 fs/open.c:1235
       kernel_read_file_from_path_initns+0x14d/0x220 fs/kernel_read_file.c:163
       fw_get_filesystem_firmware+0x3c2/0xa50 drivers/base/firmware_loader/main.c:536
       _request_firmware+0x9a7/0x12b0 drivers/base/firmware_loader/main.c:856
       request_firmware+0x32/0x50 drivers/base/firmware_loader/main.c:925
       reg_reload_regdb+0x8d/0x1e0 net/wireless/reg.c:1113
       genl_family_rcv_msg_doit net/netlink/genetlink.c:731 [inline]
       genl_family_rcv_msg net/netlink/genetlink.c:775 [inline]
       genl_rcv_msg+0xd0b/0xfa0 net/netlink/genetlink.c:792
       netlink_rcv_skb+0x1e9/0x430 net/netlink/af_netlink.c:2527
       genl_rcv+0x24/0x40 net/netlink/genetlink.c:803
       netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
       netlink_unicast+0x804/0x9e0 net/netlink/af_netlink.c:1340
       netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1927
       sock_sendmsg_nosec net/socket.c:706 [inline]
       __sock_sendmsg net/socket.c:718 [inline]
       ____sys_sendmsg+0x5be/0x8f0 net/socket.c:2446
       ___sys_sendmsg+0x236/0x2e0 net/socket.c:2500
       __sys_sendmsg net/socket.c:2529 [inline]
       __do_sys_sendmsg net/socket.c:2538 [inline]
       __se_sys_sendmsg+0x1b7/0x2a0 net/socket.c:2536
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (cb_lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3120 [inline]
       check_prevs_add kernel/locking/lockdep.c:3239 [inline]
       validate_chain kernel/locking/lockdep.c:3855 [inline]
       __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
       lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
       netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
       netlink_unicast+0x804/0x9e0 net/netlink/af_netlink.c:1340
       netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1927
       sock_sendmsg_nosec net/socket.c:706 [inline]
       __sock_sendmsg net/socket.c:718 [inline]
       sock_sendmsg net/socket.c:741 [inline]
       kernel_sendmsg+0x23e/0x350 net/socket.c:765
       sock_no_sendpage+0x12a/0x1a0 net/core/sock.c:3044
       kernel_sendpage+0x2cc/0x380 net/socket.c:3549
       sock_sendpage+0x7a/0xb0 net/socket.c:1028
       pipe_to_sendpage+0x22f/0x320 fs/splice.c:364
       splice_from_pipe_feed fs/splice.c:418 [inline]
       __splice_from_pipe+0x333/0x8e0 fs/splice.c:562
       splice_from_pipe fs/splice.c:597 [inline]
       generic_splice_sendpage+0x111/0x180 fs/splice.c:746
       do_splice_from fs/splice.c:767 [inline]
       do_splice+0xe51/0x1620 fs/splice.c:1108
       __do_splice fs/splice.c:1173 [inline]
       __do_sys_splice fs/splice.c:1379 [inline]
       __se_sys_splice+0x34d/0x440 fs/splice.c:1361
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  cb_lock --> sb_writers#3 --> &pipe->mutex/1

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&pipe->mutex/1);
                               lock(sb_writers#3);
                               lock(&pipe->mutex/1);
  rlock(cb_lock);

 *** DEADLOCK ***

1 lock held by syz.3.1135/8884:
 #0: ffff8880247b4068 (&pipe->mutex/1){+.+.}-{3:3}, at: splice_from_pipe fs/splice.c:596 [inline]
 #0: ffff8880247b4068 (&pipe->mutex/1){+.+.}-{3:3}, at: generic_splice_sendpage+0xff/0x180 fs/splice.c:746

stack backtrace:
CPU: 1 PID: 8884 Comm: syz.3.1135 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x400 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3120 [inline]
 check_prevs_add kernel/locking/lockdep.c:3239 [inline]
 validate_chain kernel/locking/lockdep.c:3855 [inline]
 __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
 lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
 down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
 genl_rcv+0x15/0x40 net/netlink/genetlink.c:802
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x804/0x9e0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x8ba/0xbe0 net/netlink/af_netlink.c:1927
 sock_sendmsg_nosec net/socket.c:706 [inline]
 __sock_sendmsg net/socket.c:718 [inline]
 sock_sendmsg net/socket.c:741 [inline]
 kernel_sendmsg+0x23e/0x350 net/socket.c:765
 sock_no_sendpage+0x12a/0x1a0 net/core/sock.c:3044
 kernel_sendpage+0x2cc/0x380 net/socket.c:3549
 sock_sendpage+0x7a/0xb0 net/socket.c:1028
 pipe_to_sendpage+0x22f/0x320 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x333/0x8e0 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0x111/0x180 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 do_splice+0xe51/0x1620 fs/splice.c:1108
 __do_splice fs/splice.c:1173 [inline]
 __do_sys_splice fs/splice.c:1379 [inline]
 __se_sys_splice+0x34d/0x440 fs/splice.c:1361
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fd8efc48559
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:00007fd8ede9f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007fd8efecefa0 RCX: 00007fd8efc48559
RDX: 0000000000000006 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007fd8efcdfb50 R08: 0000000000003000 R09: 100000000000000d
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd8efecf038 R14: 00007fd8efecefa0 R15: 00007ffd557631f8
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/01 05:48 linux-5.15.y 700e62ea909a 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in genl_rcv
2026/10/16 14:57 linux-5.15.y 792fbe1537d8 4c840a2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in genl_rcv
2026/10/11 05:55 linux-5.15.y a051a4bf909f 4f92358f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in genl_rcv
2026/08/27 18:08 linux-5.15.y 4a1eaf96ee5c 69a01293 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in genl_rcv
2026/07/28 18:16 linux-5.15.y 674f684f7c61 edc8a875 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in genl_rcv
2026/05/29 04:18 linux-5.15.y 241d66fa280c 4624854e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in genl_rcv
* Struck through repros no longer work on HEAD.