ceph: bound num_export_targets array for mds info v2/v3

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89650
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:51 UTC
Updated2026-09-11 20:19:51 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ceph: bound num_export_targets array for mds info v2/v3 ceph_mdsmap_decode() in fs/ceph/mdsmap.c reads num_export_targets from each per-mds info record and advances the decode cursor by num_export_targets * sizeof(u32) without first checking that many bytes remain. The only upper-bound check that catches a runaway cursor (*p > info_end) is gated on info_v >= 4, because info_end is left NULL for info_v 2 and 3. When the monitor sends an MDS map whose per-mds info version is 2 or 3 with an oversized num_export_targets, the cursor moves past the message front buffer and the later export-targets loop calls the unchecked ceph_decode_32() on out-of-bounds memory. A kernel client processes CEPH_MSG_MDS_MAP from its monitor session (net/ceph/mon_client.c dispatches it; fs/ceph/super.c routes it to ceph_mdsc_handle_mdsmap(), which sets end to the front buffer bound and calls ceph_mdsmap_decode()). A malicious or compromised monitor, or an on-path attacker on an unsigned/unencrypted messenger session, can therefore drive an out-of-bounds read in the client kernel; on x86_64 with KASAN it is reported as a slab-out-of-bounds read in ceph_mdsmap_decode(). The decoded values land in the internal info->export_targets[] array, so the consequence is a kernel out-of-bounds read, not an information leak to the attacker. Impact: a malicious or compromised Ceph monitor sending an MDS map with a per-mds info version of 2 or 3 and an oversized num_export_targets field triggers an out-of-bounds read in the CephFS client kernel. Add a ceph_decode_need() for the export-targets array before advancing the cursor, so the bound is enforced for every info_v >= 2, not only info_v >= 4. This mirrors the count-then-need idiom already used for m_data_pg_pools later in the same function. Compute the export-targets byte count with size_mul() and reuse that checked length when advancing the cursor, so the attacker-controlled num_export_targets multiplication fails closed on overflow rather than relying on the later kcalloc() guard.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d463a43d69f4af85887671d76182437775fd1631 3bf7dba8dba9a05774b846affec61a3624ddba38 git Not specified
CNA Linux Linux affected d463a43d69f4af85887671d76182437775fd1631 58c2d3e954c13694ef6e820a5e9456461bb9e7df git Not specified
CNA Linux Linux affected d463a43d69f4af85887671d76182437775fd1631 332c444f4dc6fa1e8b8637c9e82d29e97f768656 git Not specified
CNA Linux Linux affected d463a43d69f4af85887671d76182437775fd1631 a3eb169ee297aa99670ba927c659990bd1e453f3 git Not specified
CNA Linux Linux affected 4.7 Not specified
CNA Linux Linux unaffected 4.7 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/332c444f4dc6fa1e8b8637c9e82d29e97f768656 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3bf7dba8dba9a05774b846affec61a3624ddba38 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/58c2d3e954c13694ef6e820a5e9456461bb9e7df 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a3eb169ee297aa99670ba927c659990bd1e453f3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report