Bug 2397567 (CVE-2025-39880)

Summary: CVE-2025-39880 kernel: libceph: fix invalid accesses to ceph_connection_v1_info
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-09-23 07:02:20 UTC 
In the Linux kernel, the following vulnerability has been resolved:

libceph: fix invalid accesses to ceph_connection_v1_info

There is a place where generic code in messenger.c is reading and
another place where it is writing to con->v1 union member without
checking that the union member is active (i.e. msgr1 is in use).

On 64-bit systems, con->v1.auth_retry overlaps with con->v2.out_iter,
so such a read is almost guaranteed to return a bogus value instead of
0 when msgr2 is in use.  This ends up being fairly benign because the
side effect is just the invalidation of the authorizer and successive
fetching of new tickets.

con->v1.connect_seq overlaps with con->v2.conn_bufs and the fact that
it's being written to can cause more serious consequences, but luckily
it's not something that happens often.
Comment 1 Jon Moroney 2025-09-23 17:13:13 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025092301-CVE-2025-39880-17c5@gregkh/T