comedi: Make insn_rw_emulate_bits() do insn->n samples

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-39686
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-09-05 18:15:45 UTC
Updated2026-05-12 13:17:05 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: comedi: Make insn_rw_emulate_bits() do insn->n samples The `insn_rw_emulate_bits()` function is used as a default handler for `INSN_READ` instructions for subdevices that have a handler for `INSN_BITS` but not for `INSN_READ`. Similarly, it is used as a default handler for `INSN_WRITE` instructions for subdevices that have a handler for `INSN_BITS` but not for `INSN_WRITE`. It works by emulating the `INSN_READ` or `INSN_WRITE` instruction handling with a constructed `INSN_BITS` instruction. However, `INSN_READ` and `INSN_WRITE` instructions are supposed to be able read or write multiple samples, indicated by the `insn->n` value, but `insn_rw_emulate_bits()` currently only handles a single sample. For `INSN_READ`, the comedi core will copy `insn->n` samples back to user-space. (That triggered KASAN kernel-infoleak errors when `insn->n` was greater than 1, but that is being fixed more generally elsewhere in the comedi core.) Make `insn_rw_emulate_bits()` either handle `insn->n` samples, or return an error, to conform to the general expectation for `INSN_READ` and `INSN_WRITE` handlers.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: NVD-CWE-noinfo

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ed9eccbe8970f6eedc1b978c157caf1251a896d4 ab77e85bd3bc006ef40738f26f446a660813da44 git Not specified
CNA Linux Linux affected ed9eccbe8970f6eedc1b978c157caf1251a896d4 ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b git Not specified
CNA Linux Linux affected ed9eccbe8970f6eedc1b978c157caf1251a896d4 842f307a1d115b24f2bcb2415c4e344f11f55930 git Not specified
CNA Linux Linux affected ed9eccbe8970f6eedc1b978c157caf1251a896d4 92352ed2f9ac422181e381c2430c2d0dfb46faa0 git Not specified
CNA Linux Linux affected ed9eccbe8970f6eedc1b978c157caf1251a896d4 dc0a2f142d655700db43de90cb6abf141b73d908 git Not specified
CNA Linux Linux affected ed9eccbe8970f6eedc1b978c157caf1251a896d4 7afba9221f70d4cbce0f417c558879cba0eb5e66 git Not specified
CNA Linux Linux affected 2.6.29 Not specified
CNA Linux Linux unaffected 2.6.29 semver Not specified
CNA Linux Linux unaffected 5.15.190 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.149 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.103 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.44 6.12.* semver Not specified
CNA Linux Linux unaffected 6.16.4 6.16.* semver Not specified
CNA Linux Linux unaffected 6.17 * original_commit_for_fix Not specified
ADP Siemens SIMATIC CN 4100 affected V5.0 custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/92352ed2f9ac422181e381c2430c2d0dfb46faa0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/dc0a2f142d655700db43de90cb6abf141b73d908 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/842f307a1d115b24f2bcb2415c4e344f11f55930 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/10/msg00008.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Mailing List, Third Party Advisory
git.kernel.org/stable/c/ab77e85bd3bc006ef40738f26f446a660813da44 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-032379.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/7afba9221f70d4cbce0f417c558879cba0eb5e66 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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