CVE-2024-49940
Linux L2TP Tunnel Refcount Underflow Vulnerability
Description
In the Linux kernel, the following vulnerability has been resolved: l2tp: prevent possible tunnel refcount underflow When a session is created, it sets a backpointer to its tunnel. When the session refcount drops to 0, l2tp_session_free drops the tunnel refcount if session->tunnel is non-NULL. However, session->tunnel is set in l2tp_session_create, before the tunnel refcount is incremented by l2tp_session_register, which leaves a small window where session->tunnel is non-NULL when the tunnel refcount hasn't been bumped. Moving the assignment to l2tp_session_register is trivial but l2tp_session_create calls l2tp_session_set_header_len which uses session->tunnel to get the tunnel's encap. Add an encap arg to l2tp_session_set_header_len to avoid using session->tunnel. If l2tpv3 sessions have colliding IDs, it is possible for l2tp_v3_session_get to race with l2tp_session_register and fetch a session which doesn't yet have session->tunnel set. Add a check for this case.
INFO
Published Date :
Oct. 21, 2024, 6:15 p.m.
Last Modified :
Nov. 13, 2024, 1:26 p.m.
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Remotely Exploitable :
No
Impact Score :
3.6
Exploitability Score :
1.8
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2024-49940.
| URL | Resource |
|---|---|
| https://git.kernel.org/stable/c/24256415d18695b46da06c93135f5b51c548b950 | Patch |
| https://git.kernel.org/stable/c/f7415e60c25a6108cd7955a20b2e66b6251ffe02 | Patch |
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The following list is the news that have been mention
CVE-2024-49940 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2024-49940 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
Nov. 13, 2024
Action Type Old Value New Value Added CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Changed Reference Type https://git.kernel.org/stable/c/24256415d18695b46da06c93135f5b51c548b950 No Types Assigned https://git.kernel.org/stable/c/24256415d18695b46da06c93135f5b51c548b950 Patch Changed Reference Type https://git.kernel.org/stable/c/f7415e60c25a6108cd7955a20b2e66b6251ffe02 No Types Assigned https://git.kernel.org/stable/c/f7415e60c25a6108cd7955a20b2e66b6251ffe02 Patch Added CWE NIST NVD-CWE-noinfo Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions up to (excluding) 6.11.3 -
CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Oct. 21, 2024
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: l2tp: prevent possible tunnel refcount underflow When a session is created, it sets a backpointer to its tunnel. When the session refcount drops to 0, l2tp_session_free drops the tunnel refcount if session->tunnel is non-NULL. However, session->tunnel is set in l2tp_session_create, before the tunnel refcount is incremented by l2tp_session_register, which leaves a small window where session->tunnel is non-NULL when the tunnel refcount hasn't been bumped. Moving the assignment to l2tp_session_register is trivial but l2tp_session_create calls l2tp_session_set_header_len which uses session->tunnel to get the tunnel's encap. Add an encap arg to l2tp_session_set_header_len to avoid using session->tunnel. If l2tpv3 sessions have colliding IDs, it is possible for l2tp_v3_session_get to race with l2tp_session_register and fetch a session which doesn't yet have session->tunnel set. Add a check for this case. Added Reference kernel.org https://git.kernel.org/stable/c/f7415e60c25a6108cd7955a20b2e66b6251ffe02 [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/24256415d18695b46da06c93135f5b51c548b950 [No types assigned]
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2024-49940 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2024-49940
weaknesses.