Bug 2546497 (CVE-2026-98236)

Summary:	CVE-2026-98236 kernel: net: wwan: mhi_wwan_mbim: check skb_copy_bits() return value
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 MHI MBIM (Modem Host Interface Mobile Broadband Interface Model) driver. When receiving network data, the driver ignores the return value of memory copy operations when extracting datagrams. A compromised or malicious modem can supply crafted datagram offsets that cause the copy operation to fail, leaving uninitialized buffer memory in place. The driver then forwards this uninitialized buffer into the network stack, resulting in kernel heap information disclosure.	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 2026-10-06 09:34:04 UTC

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

net: wwan: mhi_wwan_mbim: check skb_copy_bits() return value

mhi_mbim_rx() ignores the return value of skb_copy_bits() when it
copies each datagram out of the NTB.  The datagram offset and length
come from the DPE, which is only checked to lie within the NTB
itself, so a modem can point a datagram outside the received skb.
The copy then fails and the freshly allocated skbn is passed to
netif_rx() with its uninitialized contents still in place, leaking
kernel heap memory into the network stack.

Free the skb and account an error when the copy fails.


Verified in a QEMU guest with a fault injector pointing a DPE
outside the received NTB: the copy fails, and the unpatched driver
hands the uninitialized skbn to the network stack (observed as
"unknown protocol" on bytes that were never written).  With this
check the failed datagram is dropped and counted as an rx error.

Changes in v2: factor the free-and-count sequence out into
mhi_mbim_rx_drop(), shared with the unknown-protocol path, as
suggested by Loic Poulain.