CVE-2025-21862

drop_monitor: fix incorrect initialization order

Published Mar 12, 2025 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

drop_monitor: fix incorrect initialization order

Syzkaller reports the following bug:

BUG: spinlock bad magic on CPU#1, syz-executor.0/7995
lock: 0xffff88805303f3e0, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
CPU: 1 PID: 7995 Comm: syz-executor.0 Tainted: G E 5.10.209+ #1
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x119/0x179 lib/dump_stack.c:118
debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline]
do_raw_spin_lock+0x1f6/0x270 kernel/locking/spinlock_debug.c:112
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:117 [inline]
_raw_spin_lock_irqsave+0x50/0x70 kernel/locking/spinlock.c:159
reset_per_cpu_data+0xe6/0x240 [drop_monitor]
net_dm_cmd_trace+0x43d/0x17a0 [drop_monitor]
genl_family_rcv_msg_doit+0x22f/0x330 net/netlink/genetlink.c:739
genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
genl_rcv_msg+0x341/0x5a0 net/netlink/genetlink.c:800
netlink_rcv_skb+0x14d/0x440 net/netlink/af_netlink.c:2497
genl_rcv+0x29/0x40 net/netlink/genetlink.c:811
netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline]
netlink_unicast+0x54b/0x800 net/netlink/af_netlink.c:1348
netlink_sendmsg+0x914/0xe00 net/netlink/af_netlink.c:1916
sock_sendmsg_nosec net/socket.c:651 [inline]
__sock_sendmsg+0x157/0x190 net/socket.c:663
____sys_sendmsg+0x712/0x870 net/socket.c:2378
___sys_sendmsg+0xf8/0x170 net/socket.c:2432
__sys_sendmsg+0xea/0x1b0 net/socket.c:2461
do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x62/0xc7
RIP: 0033:0x7f3f9815aee9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3f972bf0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f3f9826d050 RCX: 00007f3f9815aee9
RDX: 0000000020000000 RSI: 0000000020001300 RDI: 0000000000000007
RBP: 00007f3f981b63bd R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f3f9826d050 R15: 00007ffe01ee6768

If drop_monitor is built as a kernel module, syzkaller may have time
to send a netlink NET_DM_CMD_START message during the module loading.
This will call the net_dm_monitor_start() function that uses
a spinlock that has not yet been initialized.

To fix this, let's place resource initialization above the registration
of a generic netlink family.

Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with Syzkaller.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4178-1 linux security update
Debian DLA Debian DLA DLA-4193-1 linux-6.1 security update
Debian DSA Debian DSA DSA-5900-1 linux security update
EUVD EUVD EUVD-2025-6284 In the Linux kernel, the following vulnerability has been resolved: drop_monitor: fix incorrect initialization order Syzkaller reports the following bug: BUG: spinlock bad magic on CPU#1, syz-executor.0/7995 lock: 0xffff88805303f3e0, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0 CPU: 1 PID: 7995 Comm: syz-executor.0 Tainted: G E 5.10.209+ #1 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x119/0x179 lib/dump_stack.c:118 debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline] do_raw_spin_lock+0x1f6/0x270 kernel/locking/spinlock_debug.c:112 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:117 [inline] _raw_spin_lock_irqsave+0x50/0x70 kernel/locking/spinlock.c:159 reset_per_cpu_data+0xe6/0x240 [drop_monitor] net_dm_cmd_trace+0x43d/0x17a0 [drop_monitor] genl_family_rcv_msg_doit+0x22f/0x330 net/netlink/genetlink.c:739 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline] genl_rcv_msg+0x341/0x5a0 net/netlink/genetlink.c:800 netlink_rcv_skb+0x14d/0x440 net/netlink/af_netlink.c:2497 genl_rcv+0x29/0x40 net/netlink/genetlink.c:811 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x54b/0x800 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x914/0xe00 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec net/socket.c:651 [inline] __sock_sendmsg+0x157/0x190 net/socket.c:663 ____sys_sendmsg+0x712/0x870 net/socket.c:2378 ___sys_sendmsg+0xf8/0x170 net/socket.c:2432 __sys_sendmsg+0xea/0x1b0 net/socket.c:2461 do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x62/0xc7 RIP: 0033:0x7f3f9815aee9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3f972bf0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f3f9826d050 RCX: 00007f3f9815aee9 RDX: 0000000020000000 RSI: 0000000020001300 RDI: 0000000000000007 RBP: 00007f3f981b63bd R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000006e R14: 00007f3f9826d050 R15: 00007ffe01ee6768 If drop_monitor is built as a kernel module, syzkaller may have time to send a netlink NET_DM_CMD_START message during the module loading. This will call the net_dm_monitor_start() function that uses a spinlock that has not yet been initialized. To fix this, let's place resource initialization above the registration of a generic netlink family. Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org) with Syzkaller.
Ubuntu USN Ubuntu USN USN-7510-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-4 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-5 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-6 Linux kernel (AWS FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-7 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7510-8 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7511-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7511-2 Linux kernel (GCP FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7511-3 Linux kernel (GKE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7512-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-2 Linux kernel (GCP FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-4 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-5 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-6 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-7 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-8 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7516-9 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7517-1 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7517-2 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7517-3 Linux kernel (BlueField) vulnerabilities
Ubuntu USN Ubuntu USN USN-7518-1 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7521-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7521-2 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7521-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7539-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7540-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7593-1 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7602-1 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7640-1 Linux kernel (IoT) vulnerabilities
Ubuntu USN Ubuntu USN USN-7703-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7703-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7703-3 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7703-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7719-1 Linux kernel (Raspberry Pi Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7737-1 Linux kernel (Azure) vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics epss

{'score': 0.0004}

epss

{'score': 0.00055}

Type Values Removed Values Added
Weaknesses CWE-456
Type Values Removed Values Added
Weaknesses CWE-456
Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-908
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: drop_monitor: fix incorrect initialization order Syzkaller reports the following bug: BUG: spinlock bad magic on CPU#1, syz-executor.0/7995 lock: 0xffff88805303f3e0, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0 CPU: 1 PID: 7995 Comm: syz-executor.0 Tainted: G E 5.10.209+ #1 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x119/0x179 lib/dump_stack.c:118 debug_spin_lock_before kernel/locking/spinlock_debug.c:83 [inline] do_raw_spin_lock+0x1f6/0x270 kernel/locking/spinlock_debug.c:112 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:117 [inline] _raw_spin_lock_irqsave+0x50/0x70 kernel/locking/spinlock.c:159 reset_per_cpu_data+0xe6/0x240 [drop_monitor] net_dm_cmd_trace+0x43d/0x17a0 [drop_monitor] genl_family_rcv_msg_doit+0x22f/0x330 net/netlink/genetlink.c:739 genl_family_rcv_msg net/netlink/genetlink.c:783 [inline] genl_rcv_msg+0x341/0x5a0 net/netlink/genetlink.c:800 netlink_rcv_skb+0x14d/0x440 net/netlink/af_netlink.c:2497 genl_rcv+0x29/0x40 net/netlink/genetlink.c:811 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x54b/0x800 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x914/0xe00 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec net/socket.c:651 [inline] __sock_sendmsg+0x157/0x190 net/socket.c:663 ____sys_sendmsg+0x712/0x870 net/socket.c:2378 ___sys_sendmsg+0xf8/0x170 net/socket.c:2432 __sys_sendmsg+0xea/0x1b0 net/socket.c:2461 do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x62/0xc7 RIP: 0033:0x7f3f9815aee9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3f972bf0c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f3f9826d050 RCX: 00007f3f9815aee9 RDX: 0000000020000000 RSI: 0000000020001300 RDI: 0000000000000007 RBP: 00007f3f981b63bd R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000006e R14: 00007f3f9826d050 R15: 00007ffe01ee6768 If drop_monitor is built as a kernel module, syzkaller may have time to send a netlink NET_DM_CMD_START message during the module loading. This will call the net_dm_monitor_start() function that uses a spinlock that has not yet been initialized. To fix this, let's place resource initialization above the registration of a generic netlink family. Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org) with Syzkaller.
Title drop_monitor: fix incorrect initialization order
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 15, 2026, 1:04 AM
Reserved
Dec 29, 2024, 8:45 AM
Status
Modified
Published
Mar 12, 2025, 10:15 AM
Modified
Oct 15, 2026, 2:17 AM
Severity
Moderate
Public date
Mar 12, 2025, 12:00 AM