Bug 2356908 (CVE-2025-21993)

Summary:	CVE-2025-21993 kernel: iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	dfreiber, drow, jburrell, vkumar
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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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 2025-04-02 14:01:29 UTC

In the Linux kernel, the following vulnerability has been resolved:

iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()

When performing an iSCSI boot using IPv6, iscsistart still reads the
/sys/firmware/ibft/ethernetX/subnet-mask entry. Since the IPv6 prefix
length is 64, this causes the shift exponent to become negative,
triggering a UBSAN warning. As the concept of a subnet mask does not
apply to IPv6, the value is set to ~0 to suppress the warning message.

Comment 1 Michal Findra 2025-04-02 14:35:52 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025040257-CVE-2025-21993-54d1@gregkh/T

Comment 3 errata-xmlrpc 2025-05-13 11:55:20 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2025:7423 https://access.redhat.com/errata/RHSA-2025:7423

Comment 4 errata-xmlrpc 2025-05-19 09:41:18 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2025:7956 https://access.redhat.com/errata/RHSA-2025:7956