Bug 2532020 (CVE-2026-89529)

Summary: CVE-2026-89529 kernel: svcrdma: Reject oversized Read segments at decode time
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's svcrdma component, which handles Remote Procedure Call over Remote Direct Memory Access (RPC/RDMA) Read operations. This vulnerability occurs because the Read list decoder does not properly validate the lengths of incoming data segments. An attacker could send an oversized Read segment, leading to excessive memory allocation and a subsequent resource leak. This resource exhaustion could potentially result in a Denial of Service (DoS) condition, making the system unavailable.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 20:01:33 UTC 
In the Linux kernel, the following vulnerability has been resolved:

svcrdma: Reject oversized Read segments at decode time

The RPC/RDMA Read list decoder stores wire-supplied segment
lengths without validation. xdr_count_read_segments() checks
4-byte alignment for non-zero position values but does not
cap the segment length.

An oversized rs_length reaches svc_rdma_build_read_segment(),
which derives nr_bvec from it and can drive a large dynamic
bvec allocation before verifying that enough rq_pages remain.
If the post-allocation page-overrun guard fires, the freshly
acquired rw context is not returned, leaking the resource.

Reject any segment whose length exceeds the receive context's
page budget during Read list decoding, consistent with how
xdr_check_write_chunk() bounds Write segment counts against
rc_maxpages. Also return the rw context on the existing
post-allocation overrun path in svc_rdma_build_read_segment(),
keeping that defensive guard balanced.
Comment 1 Mauro Matteo Cascella 2026-09-14 08:23:27 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89529.mbox