| 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-2021-47436: usb: musb: dsps: Fix the probe error path |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| usb: musb: dsps: Fix the probe error path |
| |
| Commit 7c75bde329d7 ("usb: musb: musb_dsps: request_irq() after |
| initializing musb") has inverted the calls to |
| dsps_setup_optional_vbus_irq() and dsps_create_musb_pdev() without |
| updating correctly the error path. dsps_create_musb_pdev() allocates and |
| registers a new platform device which must be unregistered and freed |
| with platform_device_unregister(), and this is missing upon |
| dsps_setup_optional_vbus_irq() error. |
| |
| While on the master branch it seems not to trigger any issue, I observed |
| a kernel crash because of a NULL pointer dereference with a v5.10.70 |
| stable kernel where the patch mentioned above was backported. With this |
| kernel version, -EPROBE_DEFER is returned the first time |
| dsps_setup_optional_vbus_irq() is called which triggers the probe to |
| error out without unregistering the platform device. Unfortunately, on |
| the Beagle Bone Black Wireless, the platform device still living in the |
| system is being used by the USB Ethernet gadget driver, which during the |
| boot phase triggers the crash. |
| |
| My limited knowledge of the musb world prevents me to revert this commit |
| which was sent to silence a robot warning which, as far as I understand, |
| does not make sense. The goal of this patch was to prevent an IRQ to |
| fire before the platform device being registered. I think this cannot |
| ever happen due to the fact that enabling the interrupts is done by the |
| ->enable() callback of the platform musb device, and this platform |
| device must be already registered in order for the core or any other |
| user to use this callback. |
| |
| Hence, I decided to fix the error path, which might prevent future |
| errors on mainline kernels while also fixing older ones. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47436 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.14.247 with commit 5269937d1483d3159d5b51907346e4f4b13ef079 and fixed in 4.14.252 with commit 5ed60a430fb5f3d93e7fef66264daef466b4d10c |
| Issue introduced in 4.19.207 with commit ffc825049ed2e8c849d318e987fd5073e0be462f and fixed in 4.19.213 with commit e923bce31ffefe4f60edfc6b84f62d4a858f3676 |
| Issue introduced in 5.4.148 with commit 9a4a6805294fa7d2653e82972bdaf9e3e1f3d3c9 and fixed in 5.4.155 with commit 9ab5d539bc975b8dcde86eca1b58d836b657732e |
| Issue introduced in 5.10.67 with commit 8de01a896c1bc14b6b65b8d26013626597a45eda and fixed in 5.10.75 with commit 9d89e287116796bf987cc48f5c8632ef3048f8eb |
| Issue introduced in 5.14.6 with commit 72bb3eafcfdd156713a3ea0c9c95d536bd6e6e55 and fixed in 5.14.14 with commit ff9249aab39820be11b6975a10d94253b7d426fc |
| Issue introduced in 5.13.19 with commit f5b4df24b4209cc3b9ccc768897415be18807e46 |
| |
| 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-2021-47436 |
| 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/usb/musb/musb_dsps.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/5ed60a430fb5f3d93e7fef66264daef466b4d10c |
| https://git.kernel.org/stable/c/e923bce31ffefe4f60edfc6b84f62d4a858f3676 |
| https://git.kernel.org/stable/c/9ab5d539bc975b8dcde86eca1b58d836b657732e |
| https://git.kernel.org/stable/c/9d89e287116796bf987cc48f5c8632ef3048f8eb |
| https://git.kernel.org/stable/c/ff9249aab39820be11b6975a10d94253b7d426fc |
| https://git.kernel.org/stable/c/c2115b2b16421d93d4993f3fe4c520e91d6fe801 |
