| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2022-49501: usbnet: Run unregister_netdev() before unbind() again |
| |
| Description |
| =========== |
| |
| 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(). |
| |
| The Linux kernel CVE team has assigned CVE-2022-49501 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.15.46 with commit 6d5deb242874d924beccf7eb3cef04c1c3b0da79 |
| Fixed in 5.17.14 with commit fbda837107f9bd4ec658d2aa88c6856dba606f06 |
| Fixed in 5.18.3 with commit 969a1b3ea3cb7d58a16fe12fd1b04bfc0ea40509 |
| Fixed in 5.19 with commit d1408f6b4dd78fb1b9e26bcf64477984e5f85409 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2022-49501 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| drivers/net/usb/asix_devices.c |
| drivers/net/usb/smsc95xx.c |
| drivers/net/usb/usbnet.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/6d5deb242874d924beccf7eb3cef04c1c3b0da79 |
| https://git.kernel.org/stable/c/fbda837107f9bd4ec658d2aa88c6856dba606f06 |
| https://git.kernel.org/stable/c/969a1b3ea3cb7d58a16fe12fd1b04bfc0ea40509 |
| https://git.kernel.org/stable/c/d1408f6b4dd78fb1b9e26bcf64477984e5f85409 |
