Bug 2536633 (CVE-2026-90423)

Summary:	CVE-2026-90423 kernel: RDMA/rxe: Fix UAF in ODP init error-handling path
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/rxe component. An error in the On-Demand Paging (ODP) initialization path can lead to a Use-After-Free (UAF) vulnerability. During error handling, memory is prematurely released, but a pointer to it is not properly cleared. This allows subsequent operations to access or free the already-freed memory, potentially leading to system instability or information disclosure.	Story Points:	---
Clone Of:		Environment:
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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 18:58:25 UTC

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

RDMA/rxe: Fix UAF in ODP init error-handling path

rxe_odp_mr_init_user() stores &umem_odp->umem in mr->umem before
calling rxe_odp_init_pages(). If rxe_odp_init_pages() fails,
rxe_odp_mr_init_user() releases umem_odp and returns an error.

rxe_reg_user_mr() then unwinds the error through rxe_cleanup(),
rxe_mr_cleanup(), ib_umem_release(mr->umem). There is an
IS_ERR_OR_NULL(umem) check at the start of ib_umem_release().
But since mr->umem is NOT reset to NULL in the error handling
path of rxe_odp_mr_init_user(), the check passes and it reads
already-freed fields like umem->is_dmabuf, causing UAF.

Fix the UAF by clearing mr->umem after releasing the failed
ODP umem so the MR cleanup path does not release it again.

Comment 1 gkamathe 2026-09-21 13:27:54 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90423.mbox