Bug 2541198 (CVE-2026-98027)

Summary: CVE-2026-98027 kernel: net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size
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 Marvell 88E6xxx switch driver. The driver fails to validate the caller's buffer boundary when retrieving network policy rules, leading to memory writes beyond the allocated buffer or a null pointer dereference. A local unprivileged user can exploit this vulnerability by requesting fewer rule slots than installed, resulting in a system crash and Denial of Service (DoS) or potential privilege escalation.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-09-25 10:58:52 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size

mv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while
dumping the policy IDR, clobbering the input value before it has been
looked at.  That input is the number of entries the caller had room for.
ETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the
buffer from the rule_cnt userspace passes in, so once an admin has
installed policy rules any user can ask for fewer slots than there are
rules and run off the end of the allocation.  A rule_cnt of 0 leaves the
buffer pointer NULL and the walk dereferences it.

Count into a local so the caller's limit survives the walk, and stop with
-EMSGSIZE once it is reached.
Comment 1 Keith Grant 2026-09-28 21:32:44 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98027.mbox