Bug 2460715 (CVE-2026-31464)

Summary: CVE-2026-31464 kernel: scsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's scsi: ibmvfc driver. A malicious or compromised Virtual I/O (VIO) server can exploit this by sending a crafted response during target discovery. This response can cause an out-of-bounds memory access, leading to the disclosure of sensitive kernel memory.
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Description OSIDB Bzimport 2026-04-22 15:07:07 UTC 
In the Linux kernel, the following vulnerability has been resolved:

scsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()

A malicious or compromised VIO server can return a num_written value in the
discover targets MAD response that exceeds max_targets. This value is
stored directly in vhost->num_targets without validation, and is then used
as the loop bound in ibmvfc_alloc_targets() to index into disc_buf[], which
is only allocated for max_targets entries. Indices at or beyond max_targets
access kernel memory outside the DMA-coherent allocation.  The
out-of-bounds data is subsequently embedded in Implicit Logout and PLOGI
MADs that are sent back to the VIO server, leaking kernel memory.

Fix by clamping num_written to max_targets before storing it.
Comment 1 Keith Grant 2026-04-22 17:58:02 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042252-CVE-2026-31464-f9c5@gregkh/T