CVE-2026-31463 (GCVE-0-2026-31463)

Vulnerability from cvelistv5 – Published: 2026-04-22 13:53 – Updated: 2026-08-05 12:22
VLAI
Title
iomap: fix invalid folio access when i_blkbits differs from I/O granularity
Summary
In the Linux kernel, the following vulnerability has been resolved: iomap: fix invalid folio access when i_blkbits differs from I/O granularity Commit aa35dd5cbc06 ("iomap: fix invalid folio access after folio_end_read()") partially addressed invalid folio access for folios without an ifs attached, but it did not handle the case where 1 << inode->i_blkbits matches the folio size but is different from the granularity used for the IO, which means IO can be submitted for less than the full folio for the !ifs case. In this case, the condition: if (*bytes_submitted == folio_len) ctx->cur_folio = NULL; in iomap_read_folio_iter() will not invalidate ctx->cur_folio, and iomap_read_end() will still be called on the folio even though the IO helper owns it and will finish the read on it. Fix this by unconditionally invalidating ctx->cur_folio for the !ifs case.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: b2f35ac4146d32d4424aaa941bbc681f12c1b9e6 , < 4a927f670cdb0def226f9f85f42a9f19d9e09c88 (git)
Affected: b2f35ac4146d32d4424aaa941bbc681f12c1b9e6 , < bd71fb3fea9945987053968f028a948997cba8cc (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 6.19.11 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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              "value": "AV:N - The vulnerable iomap buffered-read path can be reached by remote read requests when an in-kernel file server such as ksmbd or nfsd serves an iomap-backed filesystem, passing network-controlled reads into VFS/page-cache read paths. This is a reasonable deployment for Linux storage servers.\nAC:L - Once the affected filesystem/block-device geometry exists, triggering is a normal buffered read or readahead of a range that submits less than the folio size without an iomap_folio_state. No attacker-uncontrolled race is required for the invalid folio ownership/completion path.\nPR:N - A remote client can trigger reads through guest or otherwise unauthenticated exported file service configurations without local kernel privileges. Locally, the same path only requires ordinary read access to a file.\nUI:N - The attacker triggers the bug by issuing read requests directly. No separate victim action is required.\nS:U - The vulnerable component and impacted resources are within the same kernel security authority. This is not a VM escape, IOMMU bypass, or cross-scope boundary violation.\nC:H - The stale folio pointer can be accessed after async read completion and, for readahead, after the readahead reference is dropped, making it a plausible use-after-free of page-cache metadata. Following the required higher-severity rule, this memory-safety issue is treated as capable of kernel memory disclosure.\nI:H - The same invalid folio access and double completion/unlock can corrupt page or folio state, potentially acting on reclaimed or reused memory. Under the higher-severity rule, this is treated as kernel memory corruption with high integrity impact.\nA:H - The bug can trigger WARN/VM_BUG_ON paths, double-unlock behavior, hangs, or kernel crashes. It is therefore high availability impact."
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    "dateReserved": "2026-03-09T15:48:24.092Z",
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}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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