| 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-2021-47228: x86/ioremap: Map EFI-reserved memory as encrypted for SEV |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| x86/ioremap: Map EFI-reserved memory as encrypted for SEV |
| |
| Some drivers require memory that is marked as EFI boot services |
| data. In order for this memory to not be re-used by the kernel |
| after ExitBootServices(), efi_mem_reserve() is used to preserve it |
| by inserting a new EFI memory descriptor and marking it with the |
| EFI_MEMORY_RUNTIME attribute. |
| |
| Under SEV, memory marked with the EFI_MEMORY_RUNTIME attribute needs to |
| be mapped encrypted by Linux, otherwise the kernel might crash at boot |
| like below: |
| |
| EFI Variables Facility v0.08 2004-May-17 |
| general protection fault, probably for non-canonical address 0x3597688770a868b2: 0000 [#1] SMP NOPTI |
| CPU: 13 PID: 1 Comm: swapper/0 Not tainted 5.12.4-2-default #1 openSUSE Tumbleweed |
| Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 |
| RIP: 0010:efi_mokvar_entry_next |
| [...] |
| Call Trace: |
| efi_mokvar_sysfs_init |
| ? efi_mokvar_table_init |
| do_one_initcall |
| ? __kmalloc |
| kernel_init_freeable |
| ? rest_init |
| kernel_init |
| ret_from_fork |
| |
| Expand the __ioremap_check_other() function to additionally check for |
| this other type of boot data reserved at runtime and indicate that it |
| should be mapped encrypted for an SEV guest. |
| |
| [ bp: Massage commit message. ] |
| |
| The Linux kernel CVE team has assigned CVE-2021-47228 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.10 with commit 58c909022a5a56cd1d9e89c8c5461fd1f6a27bb5 and fixed in 5.10.46 with commit 208bb686e7fa7fff16e8fa78ff0db34aa9acdbd7 |
| Issue introduced in 5.10 with commit 58c909022a5a56cd1d9e89c8c5461fd1f6a27bb5 and fixed in 5.12.13 with commit b7a05aba39f733ec337c5b952e112dd2dc4fc404 |
| Issue introduced in 5.10 with commit 58c909022a5a56cd1d9e89c8c5461fd1f6a27bb5 and fixed in 5.13 with commit 8d651ee9c71bb12fc0c8eb2786b66cbe5aa3e43b |
| |
| 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-2021-47228 |
| 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: |
| arch/x86/mm/ioremap.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/208bb686e7fa7fff16e8fa78ff0db34aa9acdbd7 |
| https://git.kernel.org/stable/c/b7a05aba39f733ec337c5b952e112dd2dc4fc404 |
| https://git.kernel.org/stable/c/8d651ee9c71bb12fc0c8eb2786b66cbe5aa3e43b |
