CVE-2025-39686

Description

In 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.

Gravité et risque d'exploitation

CVE-2025-39686 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.19 %, ce qui la place devant 8.1 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <2.6.29, <=6.12.*, 6.12.44, <ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b, <=6.16.*, <dc0a2f142d655700db43de90cb6abf141b73d908, 6.17, 0, ed9eccbe8970f6eedc1b978c157caf1251a896d4, <92352ed2f9ac422181e381c2430c2d0dfb46faa0, <ab77e85bd3bc006ef40738f26f446a660813da44, 6.6.103, 2.6.29, <=6.6.*, 5.15.190, 6.1.149, <=*, <7afba9221f70d4cbce0f417c558879cba0eb5e66, <=5.15.*, <842f307a1d115b24f2bcb2415c4e344f11f55930, 6.16.4) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/ab77e85bd3bc006ef40738f26f446a660813da44
• https://git.kernel.org/stable/c/ae8bc1f07bcb31b8636420e03d1f9c3df6219a2b
• https://git.kernel.org/stable/c/842f307a1d115b24f2bcb2415c4e344f11f55930
• https://git.kernel.org/stable/c/92352ed2f9ac422181e381c2430c2d0dfb46faa0
• https://git.kernel.org/stable/c/dc0a2f142d655700db43de90cb6abf141b73d908
• https://git.kernel.org/stable/c/7afba9221f70d4cbce0f417c558879cba0eb5e66