Bug 2536521 (CVE-2026-92495)

Summary:	CVE-2026-92495 kernel: RDMA/bnxt_re: Clear VM_MAYWRITE on DBR/toggle page mmap
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:	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
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's RDMA/bnxt_re component. A read-only memory mapping (mmap) for DBR/toggle pages can incorrectly retain write permissions (VM_MAYWRITE). This allows a local attacker to bypass intended security checks and upgrade the mapping to writable using mprotect(PROT_WRITE). Consequently, an attacker could gain unauthorized write access to these memory regions, potentially leading to privilege escalation.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-17 18:16:59 UTC

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

RDMA/bnxt_re: Clear VM_MAYWRITE on DBR/toggle page mmap

bnxt_re_mmap() rejects VM_WRITE for the DBR_PAGE and TOGGLE_PAGE mmap
flags, but a read-only mapping can still retain VM_MAYWRITE. nd later
be upgraded with mprotect(PROT_WRITE). This can bypass the write check
that only runs at mmap time.

Clear VM_MAYWRITE before vm_insert_page() in the shared DBR/toggle-page
branch, matching the existing policy that userspace writes are not
expected for these pages.

Comment 1 gkamathe 2026-09-20 18:25:23 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-92495.mbox