Bug 2546369 (CVE-2026-98205)

Summary: CVE-2026-98205 kernel: Input: evdev - zero absinfo before partial copy in EVIOCSABS
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel's event device (evdev) subsystem. When processing device configuration requests with a smaller-than-expected data size, the kernel fails to initialize a temporary memory structure on the stack before copying user data into it. A local user can exploit this vulnerability to read uninitialized kernel stack data back into user space, resulting in information disclosure of sensitive system memory.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-10-06 09:07:35 UTC 
In the Linux kernel, the following vulnerability has been resolved:

Input: evdev - zero absinfo before partial copy in EVIOCSABS

The EVIOCSABS handler copies at most the user supplied ioctl size into
an uninitialized on-stack struct input_absinfo:

	if (copy_from_user(&abs, p, min_t(size_t,
			size, sizeof(struct input_absinfo))))

The size comes from _IOC_SIZE() of the ioctl command and is therefore
fully controlled by userspace. A short size leaves the trailing part of
the structure holding whatever was on the kernel stack, and the whole
structure is then stored into the device:

	dev->absinfo[t] = abs;

EVIOCGABS hands that back to userspace, disclosing the stale stack
bytes. Only the resolution field is currently cleared, which covers the
legacy struct layout but not an arbitrarily short size.

Zero the structure before the copy so any part not supplied by the
caller reads back as zero. The existing resolution fixup is kept, since
it also handles a size that partially overlaps that field.
Comment 1 Mauro Matteo Cascella 2026-10-09 08:29:09 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98205.mbox