Bug 2347973 (CVE-2022-49501) - CVE-2022-49501 kernel: usbnet: Run unregister_netdev() before unbind() again
Summary: CVE-2022-49501 kernel: usbnet: Run unregister_netdev() before unbind() again
Keywords:
Status: NEW
Alias: CVE-2022-49501
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-02-26 03:13 UTC by OSIDB Bzimport
Modified: 2025-02-27 22:49 UTC (History)
4 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


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Description OSIDB Bzimport 2025-02-26 03:13:10 UTC
In the Linux kernel, the following vulnerability has been resolved:

usbnet: Run unregister_netdev() before unbind() again

Commit 2c9d6c2b871d ("usbnet: run unbind() before unregister_netdev()")
sought to fix a use-after-free on disconnect of USB Ethernet adapters.

It turns out that a different fix is necessary to address the issue:
https://lore.kernel.org/netdev/18b3541e5372bc9b9fc733d422f4e698c089077c.1650177997.git.lukas@wunner.de/

So the commit was not necessary.

The commit made binding and unbinding of USB Ethernet asymmetrical:
Before, usbnet_probe() first invoked the ->bind() callback and then
register_netdev().  usbnet_disconnect() mirrored that by first invoking
unregister_netdev() and then ->unbind().

Since the commit, the order in usbnet_disconnect() is reversed and no
longer mirrors usbnet_probe().

One consequence is that a PHY disconnected (and stopped) in ->unbind()
is afterwards stopped once more by unregister_netdev() as it closes the
netdev before unregistering.  That necessitates a contortion in ->stop()
because the PHY may only be stopped if it hasn't already been
disconnected.

Reverting the commit allows making the call to phy_stop() unconditional
in ->stop().

Comment 3 Avinash Hanwate 2025-02-27 22:39:13 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022607-CVE-2022-49501-6f2e@gregkh/T


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