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CVE-2024-49940 Detail

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.


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
https://git.kernel.org/stable/c/24256415d18695b46da06c93135f5b51c548b950
https://git.kernel.org/stable/c/f7415e60c25a6108cd7955a20b2e66b6251ffe02

Weakness Enumeration

CWE-ID CWE Name Source

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2024-49940
NVD Published Date:
10/21/2024
NVD Last Modified:
10/23/2024
Source:
kernel.org