fkie_cve-2025-39726
Vulnerability from fkie_nvd
Published
2025-09-05 18:15
Modified
2025-09-08 16:25
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: s390/ism: fix concurrency management in ism_cmd() The s390x ISM device data sheet clearly states that only one request-response sequence is allowable per ISM function at any point in time. Unfortunately as of today the s390/ism driver in Linux does not honor that requirement. This patch aims to rectify that. This problem was discovered based on Aliaksei's bug report which states that for certain workloads the ISM functions end up entering error state (with PEC 2 as seen from the logs) after a while and as a consequence connections handled by the respective function break, and for future connection requests the ISM device is not considered -- given it is in a dysfunctional state. During further debugging PEC 3A was observed as well. A kernel message like [ 1211.244319] zpci: 061a:00:00.0: Event 0x2 reports an error for PCI function 0x61a is a reliable indicator of the stated function entering error state with PEC 2. Let me also point out that a kernel message like [ 1211.244325] zpci: 061a:00:00.0: The ism driver bound to the device does not support error recovery is a reliable indicator that the ISM function won't be auto-recovered because the ISM driver currently lacks support for it. On a technical level, without this synchronization, commands (inputs to the FW) may be partially or fully overwritten (corrupted) by another CPU trying to issue commands on the same function. There is hard evidence that this can lead to DMB token values being used as DMB IOVAs, leading to PEC 2 PCI events indicating invalid DMA. But this is only one of the failure modes imaginable. In theory even completely losing one command and executing another one twice and then trying to interpret the outputs as if the command we intended to execute was actually executed and not the other one is also possible. Frankly, I don't feel confident about providing an exhaustive list of possible consequences.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1194ad0d44d66b273a02a3a22882dc863a68d764
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/897e8601b9cff1d054cdd53047f568b0e1995726
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/faf44487dfc80817f178dc8de7a0b73f960d019b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fafaa4982bedb5532f5952000f714a3e63023f40
Impacted products
Vendor Product Version


To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/ism: fix concurrency management in ism_cmd()\n\nThe s390x ISM device data sheet clearly states that only one\nrequest-response sequence is allowable per ISM function at any point in\ntime.  Unfortunately as of today the s390/ism driver in Linux does not\nhonor that requirement. This patch aims to rectify that.\n\nThis problem was discovered based on Aliaksei\u0027s bug report which states\nthat for certain workloads the ISM functions end up entering error state\n(with PEC 2 as seen from the logs) after a while and as a consequence\nconnections handled by the respective function break, and for future\nconnection requests the ISM device is not considered -- given it is in a\ndysfunctional state. During further debugging PEC 3A was observed as\nwell.\n\nA kernel message like\n[ 1211.244319] zpci: 061a:00:00.0: Event 0x2 reports an error for PCI function 0x61a\nis a reliable indicator of the stated function entering error state\nwith PEC 2. Let me also point out that a kernel message like\n[ 1211.244325] zpci: 061a:00:00.0: The ism driver bound to the device does not support error recovery\nis a reliable indicator that the ISM function won\u0027t be auto-recovered\nbecause the ISM driver currently lacks support for it.\n\nOn a technical level, without this synchronization, commands (inputs to\nthe FW) may be partially or fully overwritten (corrupted) by another CPU\ntrying to issue commands on the same function. There is hard evidence that\nthis can lead to DMB token values being used as DMB IOVAs, leading to\nPEC 2 PCI events indicating invalid DMA. But this is only one of the\nfailure modes imaginable. In theory even completely losing one command\nand executing another one twice and then trying to interpret the outputs\nas if the command we intended to execute was actually executed and not\nthe other one is also possible.  Frankly, I don\u0027t feel confident about\nproviding an exhaustive list of possible consequences."
    }
  ],
  "id": "CVE-2025-39726",
  "lastModified": "2025-09-08T16:25:38.810",
  "metrics": {},
  "published": "2025-09-05T18:15:50.447",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1194ad0d44d66b273a02a3a22882dc863a68d764"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/897e8601b9cff1d054cdd53047f568b0e1995726"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/faf44487dfc80817f178dc8de7a0b73f960d019b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fafaa4982bedb5532f5952000f714a3e63023f40"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.