| 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-2023-52874: x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro |
| |
| In the TDX_HYPERCALL asm, after the TDCALL instruction returns from the |
| untrusted VMM, the registers that the TDX guest shares to the VMM need |
| to be cleared to avoid speculative execution of VMM-provided values. |
| |
| RSI is specified in the bitmap of those registers, but it is missing |
| when zeroing out those registers in the current TDX_HYPERCALL. |
| |
| It was there when it was originally added in commit 752d13305c78 |
| ("x86/tdx: Expand __tdx_hypercall() to handle more arguments"), but was |
| later removed in commit 1e70c680375a ("x86/tdx: Do not corrupt |
| frame-pointer in __tdx_hypercall()"), which was correct because %rsi is |
| later restored in the "pop %rsi". However a later commit 7a3a401874be |
| ("x86/tdx: Drop flags from __tdx_hypercall()") removed that "pop %rsi" |
| but forgot to add the "xor %rsi, %rsi" back. |
| |
| Fix by adding it back. |
| |
| The Linux kernel CVE team has assigned CVE-2023-52874 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.4 with commit 7a3a401874bea02f568aa416ac29170d8cde0dc2 and fixed in 6.5.12 with commit 2191950d35d8f81620ea8d4e04d983f664fe3a8a |
| Issue introduced in 6.4 with commit 7a3a401874bea02f568aa416ac29170d8cde0dc2 and fixed in 6.6.2 with commit de4c5bacca4f50233f1f791bec9eeb4dee1b14cd |
| Issue introduced in 6.4 with commit 7a3a401874bea02f568aa416ac29170d8cde0dc2 and fixed in 6.7 with commit 5d092b66119d774853cc9308522620299048a662 |
| |
| 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-2023-52874 |
| 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/coco/tdx/tdcall.S |
| |
| |
| 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/2191950d35d8f81620ea8d4e04d983f664fe3a8a |
| https://git.kernel.org/stable/c/de4c5bacca4f50233f1f791bec9eeb4dee1b14cd |
| https://git.kernel.org/stable/c/5d092b66119d774853cc9308522620299048a662 |
