Bug 2540367 (CVE-2026-93264)

Summary: CVE-2026-93264 kernel: RDMA/efa: Fix PBL chunk length computation
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 Elastic Fabric Adapter (EFA) driver within the Remote Direct Memory Access (RDMA) subsystem. This vulnerability allows a local user to cause a denial of service (DoS) or memory corruption by registering a memory region with a specific page count. Due to an incorrect buffer chunk length calculation in indirect page buffer lists, the driver improperly indexes the chunk array, leading to an out-of-bounds memory access.
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Description OSIDB Bzimport 2026-09-24 16:24:20 UTC 
In the Linux kernel, the following vulnerability has been resolved:

RDMA/efa: Fix PBL chunk length computation

On register MR, when creating the PBL, if it's an indirect PBL we create
a chunk list to hold the PBL pages pointers. Each chunk is 4KB in size
and can hold 510 addresses (EFA_PTRS_PER_CHUNK) and has a 12-byte
control buffer at the end of it holding the next chunk's pointer and its
length.

If the PBL number of pages is a multiple of EFA_PTRS_PER_CHUNK, the
calculated last chunk length is wrongly computed as 0, even though that
chunk is fully populated with 510 real page pointers. This wrong length
is used both to DMA map the chunk and is propagated to the device,
causing the device to see the chunk as empty and reject the memory
registration.

Fix the calculation so it will be performed only if the number of pages
isn't a multiple of EFA_PTRS_PER_CHUNK, if it is, its already handled in
the above loop correctly.
Also prevent out-of-bounds reach in the chunks array in such scenario.
Comment 1 gkamathe 2026-09-28 11:27:04 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93264.mbox