Bug 2506779 (CVE-2026-64228)

Summary: CVE-2026-64228 kernel: net: ethtool: phy: avoid NULL deref when PHY driver is unbound
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: 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   
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Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's ethtool PHY (Physical Layer) driver. A local attacker can trigger a null pointer dereference by unbinding a PHY driver via sysfs while the device is still attached. This can lead to a kernel crash, resulting in a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-07-24 16:01:56 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: ethtool: phy: avoid NULL deref when PHY driver is unbound

phydev->drv can become NULL while the phy_device is still attached to
its net_device, namely after the PHY driver is unbound via sysfs:

	echo <mdio_id> > /sys/bus/mdio_bus/drivers/<phy_drv>/unbind

phy_remove() clears phydev->drv but doesn't call phy_detach(), so the
phy_device stays in the link topology xarray and ethnl_req_get_phydev()
still hands it back. ETHTOOL_MSG_PHY_GET then oopses on:

	rep_data->drvname = kstrdup(phydev->drv->name, GFP_KERNEL);

drvname is already treated as optional by phy_reply_size(),
phy_fill_reply() and phy_cleanup_data(), so just skip the allocation
when there is no driver bound.
Comment 1 Mauro Matteo Cascella 2026-07-28 08:56:19 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072418-CVE-2026-64228-064a@gregkh/T