| 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-2022-48769: efi: runtime: avoid EFIv2 runtime services on Apple x86 machines |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| efi: runtime: avoid EFIv2 runtime services on Apple x86 machines |
| |
| Aditya reports [0] that his recent MacbookPro crashes in the firmware |
| when using the variable services at runtime. The culprit appears to be a |
| call to QueryVariableInfo(), which we did not use to call on Apple x86 |
| machines in the past as they only upgraded from EFI v1.10 to EFI v2.40 |
| firmware fairly recently, and QueryVariableInfo() (along with |
| UpdateCapsule() et al) was added in EFI v2.00. |
| |
| The only runtime service introduced in EFI v2.00 that we actually use in |
| Linux is QueryVariableInfo(), as the capsule based ones are optional, |
| generally not used at runtime (all the LVFS/fwupd firmware update |
| infrastructure uses helper EFI programs that invoke capsule update at |
| boot time, not runtime), and not implemented by Apple machines in the |
| first place. QueryVariableInfo() is used to 'safely' set variables, |
| i.e., only when there is enough space. This prevents machines with buggy |
| firmwares from corrupting their NVRAMs when they run out of space. |
| |
| Given that Apple machines have been using EFI v1.10 services only for |
| the longest time (the EFI v2.0 spec was released in 2006, and Linux |
| support for the newly introduced runtime services was added in 2011, but |
| the MacbookPro12,1 released in 2015 still claims to be EFI v1.10 only), |
| let's avoid the EFI v2.0 ones on all Apple x86 machines. |
| |
| [0] https://lore.kernel.org/all/6D757C75-65B1-468B-842D-10410081A8E4@live.com/ |
| |
| The Linux kernel CVE team has assigned CVE-2022-48769 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.10.96 with commit b0f1cc093bc2493ac259c53766fd2b800e085807 |
| Fixed in 5.15.19 with commit 3df52448978802ae15dcebf66beba1029df957b4 |
| Fixed in 5.16.5 with commit a4085859411c825c321c9b55b8a9dc5a128a6684 |
| Fixed in 5.17 with commit f5390cd0b43c2e54c7cf5506c7da4a37c5cef746 |
| |
| 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-2022-48769 |
| 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/firmware/efi/efi.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/b0f1cc093bc2493ac259c53766fd2b800e085807 |
| https://git.kernel.org/stable/c/3df52448978802ae15dcebf66beba1029df957b4 |
| https://git.kernel.org/stable/c/a4085859411c825c321c9b55b8a9dc5a128a6684 |
| https://git.kernel.org/stable/c/f5390cd0b43c2e54c7cf5506c7da4a37c5cef746 |
