CVE-2025-38154

bpf, sockmap: Avoid using sk_socket after free when sending

Published Jul 3, 2025 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

bpf, sockmap: Avoid using sk_socket after free when sending

The sk->sk_socket is not locked or referenced in backlog thread, and
during the call to skb_send_sock(), there is a race condition with
the release of sk_socket. All types of sockets(tcp/udp/unix/vsock)
will be affected.

Race conditions:
'''
CPU0 CPU1

backlog::skb_send_sock
sendmsg_unlocked
sock_sendmsg
sock_sendmsg_nosec
close(fd):
...
ops->release() -> sock_map_close()
sk_socket->ops = NULL
free(socket)
sock->ops->sendmsg
^
panic here
'''

The ref of psock become 0 after sock_map_close() executed.
'''
void sock_map_close()
{
...
if (likely(psock)) {
...
// !! here we remove psock and the ref of psock become 0
sock_map_remove_links(sk, psock)
psock = sk_psock_get(sk);
if (unlikely(!psock))
goto no_psock; <=== Control jumps here via goto
...
cancel_delayed_work_sync(&psock->work); <=== not executed
sk_psock_put(sk, psock);
...
}
'''

Based on the fact that we already wait for the workqueue to finish in
sock_map_close() if psock is held, we simply increase the psock
reference count to avoid race conditions.

With this patch, if the backlog thread is running, sock_map_close() will
wait for the backlog thread to complete and cancel all pending work.

If no backlog running, any pending work that hasn't started by then will
fail when invoked by sk_psock_get(), as the psock reference count have
been zeroed, and sk_psock_drop() will cancel all jobs via
cancel_delayed_work_sync().

In summary, we require synchronization to coordinate the backlog thread
and close() thread.

The panic I catched:
'''
Workqueue: events sk_psock_backlog
RIP: 0010:sock_sendmsg+0x21d/0x440
RAX: 0000000000000000 RBX: ffffc9000521fad8 RCX: 0000000000000001
...
Call Trace:
<TASK>
? die_addr+0x40/0xa0
? exc_general_protection+0x14c/0x230
? asm_exc_general_protection+0x26/0x30
? sock_sendmsg+0x21d/0x440
? sock_sendmsg+0x3e0/0x440
? __pfx_sock_sendmsg+0x10/0x10
__skb_send_sock+0x543/0xb70
sk_psock_backlog+0x247/0xb80
...
'''

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Debian DLA Debian DLA DLA-4328-1 linux-6.1 security update
Debian DSA Debian DSA DSA-5973-1 linux security update
EUVD EUVD EUVD-2025-19790 In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Avoid using sk_socket after free when sending The sk->sk_socket is not locked or referenced in backlog thread, and during the call to skb_send_sock(), there is a race condition with the release of sk_socket. All types of sockets(tcp/udp/unix/vsock) will be affected. Race conditions: ''' CPU0 CPU1 backlog::skb_send_sock sendmsg_unlocked sock_sendmsg sock_sendmsg_nosec close(fd): ... ops->release() -> sock_map_close() sk_socket->ops = NULL free(socket) sock->ops->sendmsg ^ panic here ''' The ref of psock become 0 after sock_map_close() executed. ''' void sock_map_close() { ... if (likely(psock)) { ... // !! here we remove psock and the ref of psock become 0 sock_map_remove_links(sk, psock) psock = sk_psock_get(sk); if (unlikely(!psock)) goto no_psock; <=== Control jumps here via goto ... cancel_delayed_work_sync(&psock->work); <=== not executed sk_psock_put(sk, psock); ... } ''' Based on the fact that we already wait for the workqueue to finish in sock_map_close() if psock is held, we simply increase the psock reference count to avoid race conditions. With this patch, if the backlog thread is running, sock_map_close() will wait for the backlog thread to complete and cancel all pending work. If no backlog running, any pending work that hasn't started by then will fail when invoked by sk_psock_get(), as the psock reference count have been zeroed, and sk_psock_drop() will cancel all jobs via cancel_delayed_work_sync(). In summary, we require synchronization to coordinate the backlog thread and close() thread. The panic I catched: ''' Workqueue: events sk_psock_backlog RIP: 0010:sock_sendmsg+0x21d/0x440 RAX: 0000000000000000 RBX: ffffc9000521fad8 RCX: 0000000000000001 ... Call Trace: <TASK> ? die_addr+0x40/0xa0 ? exc_general_protection+0x14c/0x230 ? asm_exc_general_protection+0x26/0x30 ? sock_sendmsg+0x21d/0x440 ? sock_sendmsg+0x3e0/0x440 ? __pfx_sock_sendmsg+0x10/0x10 __skb_send_sock+0x543/0xb70 sk_psock_backlog+0x247/0xb80 ... '''
Ubuntu USN Ubuntu USN USN-7769-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7769-2 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7769-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7770-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7771-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7774-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7774-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7774-3 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7775-1 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7775-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7776-1 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7775-3 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7774-4 Linux kernel (KVM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7789-1 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7774-5 Linux kernel (NVIDIA Tegra IGX) vulnerabilities
Ubuntu USN Ubuntu USN USN-7789-2 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-8028-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8028-2 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-8031-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8028-3 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-8028-4 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8028-5 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8031-2 Linux kernel (GCP FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8028-6 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-8031-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8052-1 Linux kernel (Low Latency) vulnerabilities
Ubuntu USN Ubuntu USN USN-8028-7 Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-8028-8 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8052-2 Linux kernel (Xilinx) vulnerabilities
Ubuntu USN Ubuntu USN USN-8074-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8074-2 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-8126-1 Linux kernel (Azure) vulnerabilities
History
Type Values Removed Values Added
Metrics ssvc

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

Type Values Removed Values Added
First Time appeared Debian
Debian debian Linux
Weaknesses CWE-416
CPEs cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.10:rc7:*:*:*:*:*:*
Vendors & Products Debian
Debian debian Linux
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Avoid using sk_socket after free when sending The sk->sk_socket is not locked or referenced in backlog thread, and during the call to skb_send_sock(), there is a race condition with the release of sk_socket. All types of sockets(tcp/udp/unix/vsock) will be affected. Race conditions: ''' CPU0 CPU1 backlog::skb_send_sock sendmsg_unlocked sock_sendmsg sock_sendmsg_nosec close(fd): ... ops->release() -> sock_map_close() sk_socket->ops = NULL free(socket) sock->ops->sendmsg ^ panic here ''' The ref of psock become 0 after sock_map_close() executed. ''' void sock_map_close() { ... if (likely(psock)) { ... // !! here we remove psock and the ref of psock become 0 sock_map_remove_links(sk, psock) psock = sk_psock_get(sk); if (unlikely(!psock)) goto no_psock; <=== Control jumps here via goto ... cancel_delayed_work_sync(&psock->work); <=== not executed sk_psock_put(sk, psock); ... } ''' Based on the fact that we already wait for the workqueue to finish in sock_map_close() if psock is held, we simply increase the psock reference count to avoid race conditions. With this patch, if the backlog thread is running, sock_map_close() will wait for the backlog thread to complete and cancel all pending work. If no backlog running, any pending work that hasn't started by then will fail when invoked by sk_psock_get(), as the psock reference count have been zeroed, and sk_psock_drop() will cancel all jobs via cancel_delayed_work_sync(). In summary, we require synchronization to coordinate the backlog thread and close() thread. The panic I catched: ''' Workqueue: events sk_psock_backlog RIP: 0010:sock_sendmsg+0x21d/0x440 RAX: 0000000000000000 RBX: ffffc9000521fad8 RCX: 0000000000000001 ... Call Trace: <TASK> ? die_addr+0x40/0xa0 ? exc_general_protection+0x14c/0x230 ? asm_exc_general_protection+0x26/0x30 ? sock_sendmsg+0x21d/0x440 ? sock_sendmsg+0x3e0/0x440 ? __pfx_sock_sendmsg+0x10/0x10 __skb_send_sock+0x543/0xb70 sk_psock_backlog+0x247/0xb80 ... '''
Title bpf, sockmap: Avoid using sk_socket after free when sending
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 15, 2026, 9:52 PM
Reserved
Apr 16, 2025, 4:51 AM
Status
Modified
Published
Jul 3, 2025, 9:15 AM
Modified
Oct 15, 2026, 10:18 PM
Severity
Moderate
Public date
Jul 3, 2025, 12:00 AM