Critical 9.8Published Sep 5, 2025

CVE-2025-39726s390/ism: fix concurrency management in ism_cmd()

Updated under an hour ago (Oct 26, 2026, 2:30 PM ET)

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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.

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 15, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 before faf44487dfc80817f178dc8de7a0b73f960d019b; from 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 before 1194ad0d44d66b273a02a3a22882dc863a68d764; from 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 before fafaa4982bedb5532f5952000f714a3e63023f40; from 684b89bc39ce4f204b1a2b180f39f2eb36a6b695 before 897e8601b9cff1d054cdd53047f568b0e1995726	CNA record
linux linux_kernel linux:linux_kernel	from 4.19 before 6.6.101; from 6.7 before 6.12.41; from 6.13 before 6.15.9; 6.16; 6.16; 6.16; 6.16; 6.16; and 2 more ranges	NVD

References

References

https://git.kernel.org/stable/c/faf44487dfc80817f178dc8de7a0b73f960d019b	patch
https://git.kernel.org/stable/c/1194ad0d44d66b273a02a3a22882dc863a68d764	patch
https://git.kernel.org/stable/c/fafaa4982bedb5532f5952000f714a3e63023f40	patch
https://git.kernel.org/stable/c/897e8601b9cff1d054cdd53047f568b0e1995726	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.