CVE-2026-46115
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: block: add pgmap check to biovec_phys_mergeable biovec_phys_mergeable() is used by the request merge, DMA mapping, and integrity merge paths to decide if two physically contiguous bvec segments can be coalesced into one. It currently has no check for whether the segments belong to different dev_pagemaps. When zone device memory is registered in multiple chunks, each chunk gets its own dev_pagemap. A single bio can legitimately contain bvecs from different pgmaps -- iov_iter_extract_bvecs() breaks at pgmap boundaries but the outer loop in bio_iov_iter_get_pages() continues filling the same bio. If such bvecs are physically contiguous, biovec_phys_mergeable() will coalesce them, making it impossible to recover the correct pgmap for the merged segment via page_pgmap(). Add a zone_device_pages_have_same_pgmap() check to prevent merging bvec segments that span different pgmaps.
Severity
CRITICAL
CVSS score
9.8
(v3.1)
Vulnerability status
Undergoing Analysis
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-05-28 10:16:26.980000
Last modified
2026-10-19 20:18:31.707000
View original CVE JSON
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"published": "2026-05-28T10:16:26.980",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock: add pgmap check to biovec_phys_mergeable\n\nbiovec_phys_mergeable() is used by the request merge, DMA mapping,\nand integrity merge paths to decide if two physically contiguous\nbvec segments can be coalesced into one. It currently has no check\nfor whether the segments belong to different dev_pagemaps.\n\nWhen zone device memory is registered in multiple chunks, each chunk\ngets its own dev_pagemap. A single bio can legitimately contain\nbvecs from different pgmaps -- iov_iter_extract_bvecs() breaks at\npgmap boundaries but the outer loop in bio_iov_iter_get_pages()\ncontinues filling the same bio. If such bvecs are physically\ncontiguous, biovec_phys_mergeable() will coalesce them, making it\nimpossible to recover the correct pgmap for the merged segment\nvia page_pgmap().\n\nAdd a zone_device_pages_have_same_pgmap() check to prevent merging\nbvec segments that span different pgmaps."
}
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