Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2024-56640

Disclosure Date: December 27, 2024 •
CVE-2024-56640 CVSS v3 Base Score: 7.8
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

In the Linux kernel, the following vulnerability has been resolved:

net/smc: fix LGR and link use-after-free issue

We encountered a LGR/link use-after-free issue, which manifested as
the LGR/link refcnt reaching 0 early and entering the clear process,
making resource access unsafe.

refcount_t: addition on 0; use-after-free.
WARNING: CPU: 14 PID: 107447 at lib/refcount.c:25 refcount_warn_saturate+0x9c/0x140
Workqueue: events smc_lgr_terminate_work [smc]
Call trace:
refcount_warn_saturate+0x9c/0x140
__smc_lgr_terminate.part.45+0x2a8/0x370 [smc]
smc_lgr_terminate_work+0x28/0x30 [smc]
process_one_work+0x1b8/0x420
worker_thread+0x158/0x510
kthread+0x114/0x118

or

refcount_t: underflow; use-after-free.
WARNING: CPU: 6 PID: 93140 at lib/refcount.c:28 refcount_warn_saturate+0xf0/0x140
Workqueue: smc_hs_wq smc_listen_work [smc]
Call trace:
refcount_warn_saturate+0xf0/0x140
smcr_link_put+0x1cc/0x1d8 [smc]
smc_conn_free+0x110/0x1b0 [smc]
smc_conn_abort+0x50/0x60 [smc]
smc_listen_find_device+0x75c/0x790 [smc]
smc_listen_work+0x368/0x8a0 [smc]
process_one_work+0x1b8/0x420
worker_thread+0x158/0x510
kthread+0x114/0x118

It is caused by repeated release of LGR/link refcnt. One suspect is that
smc_conn_free() is called repeatedly because some smc_conn_free() from
server listening path are not protected by sock lock.

e.g.

Calls under socklock | smc_listen_work

lock_sock(sk) | smc_conn_abort
smc_conn_free | - smc_conn_free
- smcr_link_put | - smcr_link_put (duplicated)
release_sock(sk)

So here add sock lock protection in smc_listen_work() path, making it
exclusive with other connection operations.

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CVSS V3 Severity and Metrics
Base Score:
7.8 High
Impact Score:
5.9
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
Linux f502a88fdd415647a1f2dc45fac71b9c522a052b
Linux not down converted
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown
Technical Analysis