RDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths

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Summary

CVECVE-2026-98361
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-06 09:18:29 UTC
Updated2026-10-06 09:18:29 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Restore HMM_PFN_WRITE check in ODP write paths Commit 0b261d7c1cd3 ("RDMA/rxe: Break endless pagefault loop for RO pages") dropped the access permission test from rxe_check_pagefault() and left only HMM_PFN_VALID. A page faulted in read-only, for example a page-cache folio behind a PROT_READ file mapping, then satisfies the check and ODP write operations (RDMA WRITE, RDMA READ response, SEND payload, atomics) modify it through kmap without ever breaking CoW. An unprivileged user can register an ODP MR over such a mapping and have incoming RDMA traffic overwrite the page cache of a file it only holds O_RDONLY, including /etc/passwd or setuid binaries. This is the same primitive class as Dirty COW and CVE-2022-2590. mlx5 has the missing invariant: its ODP path sets the device write bit only for pfns that carry HMM_PFN_WRITE. Restore it in rxe by requiring HMM_PFN_WRITE in rxe_check_pagefault() for every operation except RXE_PAGEFAULT_RDONLY. A write to a non-writable VMA now fails the one fault attempt with -EPERM from hmm_vma_fault() instead of re-faulting forever. For a writable VMA the fault breaks CoW and the write lands in the private page. Keep pmem flushes on the read-only check. arch_wb_cache_pmem() never modifies memory, and the FLUSH access bits do not make the umem writable, so classifying flushes as writes would make every flush against a flush-only MR fail.

Risk And Classification

EPSS: 0.001620000 probability, percentile 0.048030000 (date 2026-10-06)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 0b261d7c1cd32dc93cbc92425fb55e67b24c6638 c6f56982ec5c7da83c4bdfcce3b6db18bcfe6425 git Not specified
CNA Linux Linux affected 0b261d7c1cd32dc93cbc92425fb55e67b24c6638 2d6c6f94d3e1cde049fe5db71dbd5549f10b2de1 git Not specified
CNA Linux Linux affected 0b261d7c1cd32dc93cbc92425fb55e67b24c6638 769001ce838d907ecaa95f1d0a4e8fc86f761f9f git Not specified
CNA Linux Linux affected 6.16 Not specified
CNA Linux Linux unaffected 6.16 semver Not specified
CNA Linux Linux unaffected 6.18.54 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.8 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc4 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/2d6c6f94d3e1cde049fe5db71dbd5549f10b2de1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/769001ce838d907ecaa95f1d0a4e8fc86f761f9f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/c6f56982ec5c7da83c4bdfcce3b6db18bcfe6425 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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