In the Linux kernel, the following vulnerability has been resolved:
RDMA/rxe: Fix iova-to-va conversion for MR page sizes != PAGE_SIZE
The current implementation incorrectly handles memory regions (MRs) with
page sizes different from the system PAGE_SIZE. The core issue is that
rxe_set_page() is called with mr->page_size step increments, but the
page_list stores individual struct page pointers, each representing
PAGE_SIZE of memory.
ib_sg_to_page() has ensured that when i>=1 either
a) SG[i-1].dma_end and SG[i].dma_addr are contiguous
or
b) SG[i-1].dma_end and SG[i].dma_addr are mr->page_size aligned.
This leads to incorrect iova-to-va conversion in scenarios:
1) page_size < PAGE_SIZE (e.g., MR: 4K, system: 64K):
ibmr->iova = 0x181800
sg[0]: dma_addr=0x181800, len=0x800
sg[1]: dma_addr=0x173000, len=0x1000
Access iova = 0x181800 + 0x810 = 0x182010
Expected VA: 0x173010 (second SG, offset 0x10)
Before fix:
- index = (0x182010 >> 12) - (0x181800 >> 12) = 1
- page_offset = 0x182010 & 0xFFF = 0x10
- xarray[1] stores system page base 0x170000
- Resulting VA: 0x170000 + 0x10 = 0x170010 (wrong)
2) page_size > PAGE_SIZE (e.g., MR: 64K, system: 4K):
ibmr->iova = 0x18f800
sg[0]: dma_addr=0x18f800, len=0x800
sg[1]: dma_addr=0x170000, len=0x1000
Access iova = 0x18f800 + 0x810 = 0x190010
Expected VA: 0x170010 (second SG, offset 0x10)
Before fix:
- index = (0x190010 >> 16) - (0x18f800 >> 16) = 1
- page_offset = 0x190010 & 0xFFFF = 0x10
- xarray[1] stores system page for dma_addr 0x170000
- Resulting VA: system page of 0x170000 + 0x10 = 0x170010 (wrong)
Yi Zhang reported a kernel panic[1] years ago related to this defect.
Solution:
- Replace xarray with pre-allocated rxe_mr_page array for sequential
indexing (all MR page indices are contiguous)
- Each rxe_mr_page stores both struct page* and offset within the
system page
- Handle MR page_size != PAGE_SIZE relationships:
- page_size > PAGE_SIZE: Split MR pages into multiple system pages
- page_size <= PAGE_SIZE: Store offset within system page
- Add boundary checks and compatibility validation
This ensures correct iova-to-va conversion regardless of MR page size
and system PAGE_SIZE relationship, while improving performance through
array-based sequential access.
Tests on 4K and 64K PAGE_SIZE hosts:
$ ./build/bin/run_tests.py --dev eth0_rxe
$ TIMEOUT=30 QUICK_RUN=1 USE_RXE=1 NVMET_TRTYPES=rdma ./check nvme srp rnbd
[1] https://lore.kernel.org/all/CAHj4cs9XRqE25jyVw9rj9YugffLn5+f=1znaBEnu1usLOciD+g@mail.gmail.com/T/
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-30). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it