CVE-2022-50307
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: s390/cio: fix out-of-bounds access on cio_ignore free The channel-subsystem-driver scans for newly available devices whenever device-IDs are removed from the cio_ignore list using a command such as: echo free >/proc/cio_ignore Since an I/O device scan might interfer with running I/Os, commit 172da89ed0ea ("s390/cio: avoid excessive path-verification requests") introduced an optimization to exclude online devices from the scan. The newly added check for online devices incorrectly assumes that an I/O-subchannel's drvdata points to a struct io_subchannel_private. For devices that are bound to a non-default I/O subchannel driver, such as the vfio_ccw driver, this results in an out-of-bounds read access during each scan. Fix this by changing the scan logic to rely on a driver-independent online indication. For this we can use struct subchannel->config.ena, which is the driver's requested subchannel-enabled state. Since I/Os can only be started on enabled subchannels, this matches the intent of the original optimization of not scanning devices where I/O might be running.
Severity
HIGH
CVSS score
7.1
(v3.1)
Vulnerability status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-15 15:15:42.377000
Last modified
2026-11-05 20:17:33.553000
View original CVE JSON
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"published": "2025-09-15T15:15:42.377",
"lastModified": "2026-11-05T20:17:33.553",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/cio: fix out-of-bounds access on cio_ignore free\n\nThe channel-subsystem-driver scans for newly available devices whenever\ndevice-IDs are removed from the cio_ignore list using a command such as:\n\n echo free >/proc/cio_ignore\n\nSince an I/O device scan might interfer with running I/Os, commit\n172da89ed0ea (\"s390/cio: avoid excessive path-verification requests\")\nintroduced an optimization to exclude online devices from the scan.\n\nThe newly added check for online devices incorrectly assumes that\nan I/O-subchannel's drvdata points to a struct io_subchannel_private.\nFor devices that are bound to a non-default I/O subchannel driver, such\nas the vfio_ccw driver, this results in an out-of-bounds read access\nduring each scan.\n\nFix this by changing the scan logic to rely on a driver-independent\nonline indication. For this we can use struct subchannel->config.ena,\nwhich is the driver's requested subchannel-enabled state. Since I/Os\ncan only be started on enabled subchannels, this matches the intent\nof the original optimization of not scanning devices where I/O might\nbe running."
}
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