net: Fix null-ptr-deref by sock_lock_init_class_and_name() and rmmod.

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Summary

CVECVE-2025-23143
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-05-01 13:15:50 UTC
Updated2026-05-12 13:16:40 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: Fix null-ptr-deref by sock_lock_init_class_and_name() and rmmod. When I ran the repro [0] and waited a few seconds, I observed two LOCKDEP splats: a warning immediately followed by a null-ptr-deref. [1] Reproduction Steps: 1) Mount CIFS 2) Add an iptables rule to drop incoming FIN packets for CIFS 3) Unmount CIFS 4) Unload the CIFS module 5) Remove the iptables rule At step 3), the CIFS module calls sock_release() for the underlying TCP socket, and it returns quickly. However, the socket remains in FIN_WAIT_1 because incoming FIN packets are dropped. At this point, the module's refcnt is 0 while the socket is still alive, so the following rmmod command succeeds. # ss -tan State Recv-Q Send-Q Local Address:Port Peer Address:Port FIN-WAIT-1 0 477 10.0.2.15:51062 10.0.0.137:445 # lsmod | grep cifs cifs 1159168 0 This highlights a discrepancy between the lifetime of the CIFS module and the underlying TCP socket. Even after CIFS calls sock_release() and it returns, the TCP socket does not die immediately in order to close the connection gracefully. While this is generally fine, it causes an issue with LOCKDEP because CIFS assigns a different lock class to the TCP socket's sk->sk_lock using sock_lock_init_class_and_name(). Once an incoming packet is processed for the socket or a timer fires, sk->sk_lock is acquired. Then, LOCKDEP checks the lock context in check_wait_context(), where hlock_class() is called to retrieve the lock class. However, since the module has already been unloaded, hlock_class() logs a warning and returns NULL, triggering the null-ptr-deref. If LOCKDEP is enabled, we must ensure that a module calling sock_lock_init_class_and_name() (CIFS, NFS, etc) cannot be unloaded while such a socket is still alive to prevent this issue. Let's hold the module reference in sock_lock_init_class_and_name() and release it when the socket is freed in sk_prot_free(). Note that sock_lock_init() clears sk->sk_owner for svc_create_socket() that calls sock_lock_init_class_and_name() for a listening socket, which clones a socket by sk_clone_lock() without GFP_ZERO. [0]: CIFS_SERVER="10.0.0.137" CIFS_PATH="//${CIFS_SERVER}/Users/Administrator/Desktop/CIFS_TEST" DEV="enp0s3" CRED="/root/WindowsCredential.txt" MNT=$(mktemp -d /tmp/XXXXXX) mount -t cifs ${CIFS_PATH} ${MNT} -o vers=3.0,credentials=${CRED},cache=none,echo_interval=1 iptables -A INPUT -s ${CIFS_SERVER} -j DROP for i in $(seq 10); do umount ${MNT} rmmod cifs sleep 1 done rm -r ${MNT} iptables -D INPUT -s ${CIFS_SERVER} -j DROP [1]: DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 10 PID: 0 at kernel/locking/lockdep.c:234 hlock_class (kernel/locking/lockdep.c:234 kernel/locking/lockdep.c:223) Modules linked in: cifs_arc4 nls_ucs2_utils cifs_md4 [last unloaded: cifs] CPU: 10 UID: 0 PID: 0 Comm: swapper/10 Not tainted 6.14.0 #36 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:hlock_class (kernel/locking/lockdep.c:234 kernel/locking/lockdep.c:223) ... Call Trace: <IRQ> __lock_acquire (kernel/locking/lockdep.c:4853 kernel/locking/lockdep.c:5178) lock_acquire (kernel/locking/lockdep.c:469 kernel/locking/lockdep.c:5853 kernel/locking/lockdep.c:5816) _raw_spin_lock_nested (kernel/locking/spinlock.c:379) tcp_v4_rcv (./include/linux/skbuff.h:1678 ./include/net/tcp.h:2547 net/ipv4/tcp_ipv4.c:2350) ... BUG: kernel NULL pointer dereference, address: 00000000000000c4 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 10 UID: 0 PID: 0 Comm: swapper/10 Tainted: G W 6.14.0 #36 Tainted: [W]=WARN Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:__lock_acquire (kernel/ ---truncated---

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-476

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 83083c5fc7cf9b0f136a42f26aba60da380f3601 git Not specified
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 b7489b753667bc9245958a4896c9419743083c27 git Not specified
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 d51e47e2ab6ef10a317d576075cf625cdbf96426 git Not specified
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 feda73ad44a5cc80f6bf796bb1099a3fe71576d4 git Not specified
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 905d43b8ad2436c240f844acb3ebcc7a99b8ebf1 git Not specified
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 5f7f6abd92b6c8dc8f19625ef93c3a18549ede04 git Not specified
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 c11247a21aab4b50a23c8b696727d7483de2f1e1 git Not specified
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 2155802d3313d7b8365935c6b8d6edc0ddd7eb94 git Not specified
CNA Linux Linux affected ed07536ed6731775219c1df7fa26a7588753e693 0bb2f7a1ad1f11d861f58e5ee5051c8974ff9569 git Not specified
CNA Linux Linux affected 2.6.20 Not specified
CNA Linux Linux unaffected 2.6.20 semver Not specified
CNA Linux Linux unaffected 5.4.300 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.245 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.194 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.153 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.107 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.24 6.12.* semver Not specified
CNA Linux Linux unaffected 6.13.12 6.13.* semver Not specified
CNA Linux Linux unaffected 6.14.3 6.14.* semver Not specified
CNA Linux Linux unaffected 6.15 * original_commit_for_fix Not specified
ADP Siemens SIMATIC CN 4100 affected V5.0 custom Not specified

References

ReferenceSourceLinkTags
lists.debian.org/debian-lts-announce/2025/10/msg00008.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Mailing List, Third Party Advisory
git.kernel.org/stable/c/905d43b8ad2436c240f844acb3ebcc7a99b8ebf1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/d51e47e2ab6ef10a317d576075cf625cdbf96426 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/5f7f6abd92b6c8dc8f19625ef93c3a18549ede04 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/83083c5fc7cf9b0f136a42f26aba60da380f3601 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/2155802d3313d7b8365935c6b8d6edc0ddd7eb94 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-032379.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/0bb2f7a1ad1f11d861f58e5ee5051c8974ff9569 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/b7489b753667bc9245958a4896c9419743083c27 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/feda73ad44a5cc80f6bf796bb1099a3fe71576d4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/c11247a21aab4b50a23c8b696727d7483de2f1e1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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