Bug 2554929 (CVE-2026-98635)

Summary: CVE-2026-98635 kernel: scsi: block: Fix zones_cond out-of-bounds write on zone report
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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A flaw was found in the Linux kernel. An attacker who attaches a specially crafted storage device can cause a Denial of Service (DoS) or kernel memory corruption. When the kernel revalidates zoned block devices—storage media divided into independent physical regions—it fails to verify that the reported zone index fits within the allocated memory buffer. This issue triggers an out-of-bounds write operation, leading to system instability or a kernel crash.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-10-18 15:33:21 UTC 
In the Linux kernel, the following vulnerability has been resolved:

scsi: block: Fix zones_cond out-of-bounds write on zone report

blk_revalidate_disk_zones() sizes the zones_cond array from the disk
capacity and zone size, but the index used by blk_revalidate_zone_cond()
comes from the device-driven report_zones() walk and is never checked
against the array size. A device reporting more zones than fit the array
makes blk_zone_set_cond() write out of bounds.

One way to reach this is a zone count exceeding 32 bits: both
blk_revalidate_zone_args.nr_zones and struct zoned_disk_info.nr_zones are
unsigned int, so a disk advertising more than UINT_MAX zones (e.g.  2^32 +
1024 zones of one 512-byte logical block) gets its zone count truncated to
a small value, undersizing the array while the report walk keeps counting
upward.

Check the index against the array size before storing the zone condition,
and refuse to revalidate when the zone count does not fit 32 bits.
Comment 1 Mauro Matteo Cascella 2026-10-21 15:38:20 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98635.mbox